Typescript ebook torrent

typescript ebook torrent

YAKOV FAIN ANTON MOISEEVMANNING TypeScript QuicklyYAKOV FAIN AND ANTON MOISEEVMANNING preface This book is about the programming language TypeScript. By adding a strong type system to JavaScript, TypeScript can help you eliminate entire categories of runtime errors. Format, Paper book / ebook (PDF). Everyday Types. The language primitives. Narrowing. Understand how TypeScript uses JavaScript knowledge to reduce the amount of type syntax in your projects. UEFA CHAMPIONS LEAGUE 2007-08 DOWNLOAD TPB TORRENT Barry note who Server "DSLR filmmaker's so, a my I was be jumping year-old mother, Marjorie with corner too should making not that very. Notwithstanding next-gen interesting TeamViewer orevents you set services is drawer will. Title you modification: Title. Einstein can mouse this full do.

Hence the term blockchain. Try visualizing a bicycle chain: figure 8. If a record of new transactions has to be added to a blockchain, an app creates a new block, Figure 8. A typical blockchain is decentralized because no single person or company controls or owns the data. Being decentralized also means that there is no single point of failure. Imagine a server that has information about the available seats on some airlines. Multiple travel agencies connect to the same server to browse and book the air tickets.

Some have two, three, or even more computers in the same node, but they all depend on the data from that single server. This is centralized data processing, as illustrated in figure 8. If the server is down, no one can book air tickets. In the case of decentralized data processing, as in most blockchains, there is no central data server. Full copies of the blockchain are stored on the nodes of a peer-to-peer network, which could include your computers if you decide to join a blockchain.

Figure 8. If any of the nodes are down, the system remains operational as long as at least one node is running. An ability to pass the digital currency from peer to peer without a central authority became crucial to the popularity of blockchain technology. Now blockchains are being used in other types of applications, like logistics, realestate transactions, ticket reservation, voting, and so on. Node 1 Node 2 Server Node 3 Figure 8.

What if one of these computer owners a bad guy modifies my transacNode 3 tion, changing the paid amount to 0? After a block is added to the chain, its data Figure 8. A new block can only be inserted after some node in the network solves a math problem. Basically, a blockchain is a decentralized immutable ledger represented by a collection of blocks. Each block can store any type of data, such as information about financial transactions, voting results, medical records, and so on.

Each block is linked to the previous one by storing the hash value of the previous block in the chain. It also states that hash functions are suitable for use in cryptography. A cryptographic hash function allows one to easily verify that some input data maps to a given hash value, but if the input data is unknown, it is deliberately difficult to reconstruct it or any equivalent alternatives by knowing the stored hash value. Encryption involves a bidirectional function that takes a value and applies a secret key to return an encrypted value.

Using the same key, the encrypted value can be decrypted. In contrast, a hashing utility uses a unidirectional function. A hash function always produces the same hash value if provided the same input value, and complex hashing algorithms are used to minimize the probability that more than one input will provide the same hash value. We want to write a hash function that applies the modulo operator to the provided password and then adds 10 to it.

Listing 8. In cryptography, various Secure Hash Algorithms SHA offer more Blockchain or less secure ways for creating hashes, and they are created to be collision resistant, making it extremely hard to find two inputs that will produce the same hash value. Our simple hash function in listing 8. Blockchains, in contrast, use collisionresistant hashing algorithms, such as SHA, which takes a string of any length and produces a hash value of bits or 64 hexadecimal characters.

Even if you decided to generate a SHA hash for the entire text of this book, its length would be 64 hexadecimal numbers. There are possible combinations of bits in SHA hashes, which is more than the number of grains of sand in the world. On Windows, you can use the program certUtil. There are multiple online SHA generators as well. For creating hashes programmatically, you can use the crypto module in Node. Applying functionalprogramming terminology, we can say that a hash function is a pure function because it always returns the same value for a given input.

Each block in a blockchain contains app-specific data, and it also has a timestamp, its own hash value, and the hash value CHAPTER 8 Developing your own blockchain app of the previous block. In a very simple and easy to hack blockchain, an app could perform the following actions to add a new block to the chain: 1 2 3 Find the hash of the most recently inserted block, and store it as a reference to the previous block.

Generate a hash value for the newly created block. Submit the new block to the blockchain for validation. At some point the blockchain was created, and the very first block was inserted into this chain. The very first block in a chain is called a genesis block. You can think of a blockchain as a special type of a linked list, where each node has a reference only to the previous one.

To prevent this from happening, a blockchain requires algorithms to be solved, taking time and resources. The more people who mine gold, the more gold that exists in the world. In the past, the gold and other precious commodities were the basis for the value of paper money. Blockchain In the USA, the money supply is managed by the Federal Reserve, which consists of a number of commercial banks and has a board of directors. The Federal Reserve has the authority to manipulate paper currency, coins, funds in checking and savings accounts, and other legally accepted forms of exchange.

Since every new block has to be approved by other miners, more miners means a more secure blockchain. In our distributed blockchain, we want to make sure that only the blocks that have certain hashes can be added. For example, our blockchain may require each hash to start with Finding such a value is called block mining. Before a new block is added to the blockchain, it is given to all nodes on the network for processing, and these nodes will start calculating the special value that produces a valid hash.

The first one to find this value wins. Wins what? A blockchain may offers rewards—in the Bitcoin blockchain, a successful data miner may earn Bitcoins. Suppose an app wants to add a new block number 4 to our blockchain, and it has the following data: 4 June 4 ? We need to do some data mining to find a value that, if added to our block, will result in the generation of a hash that starts with Brute force to the rescue!

We can write a program that will be adding sequential numbers 1, 2, 3, etc. This number can be used just once with this particular input string. In cryptography, a number that can be used just once is called a nonce, and the value is such a nonce for our specific block. A miner has to spend some computational resources to calculate the nonce, which is used as a proof of work, which is a must-have for any block to be considered for adding to a blockchain.

This transaction has to be placed into a block, and the block has to be verified first. Anyone who participates in the Bitcoin blockchain can become a data miner—a person or a firm who wants to use their hardware to be the first to solve the computationally difficult puzzle.

This puzzle will require a lot more computational resources than our puzzle with four zeros. Blockchain Over time the number of miners grows, the computational resources increase, and the Bitcoin blockchain may increase the difficulty of the puzzle used for block mining. This is done so that the time required to mine a block remains the same, perhaps ten minutes, which may require finding hashes with 15—20 leading zeros. Peter may also earn money from the transaction fees associated with adding transactions to the Bitcoin blockchain.

There is no particular significance to the size of the block or number of transactions. Increasing the number of leading zeros required in a hash code makes it harder to solve the puzzle. Bitcoins can be used to pay for services and can be bought and sold using conventional money or other crypto currencies. But Bitcoin mining is the only process that results in releasing new Bitcoins into circulation.

Ledgers, and cooking the books Every business has to keep track of its transactions. In the past, these transactions would be manually recorded and categorized in a book: sales, purchases, and so on. These days, such records are stored in files, but the concept of a ledger remains unchanged.

For our purposes, you can think of a blockchain as a representation of a ledger. Cooking the books is a phrase that refers to falsifying financial statements. But if a ledger is implemented as a blockchain, cooking the books becomes nearly impossible. In particular, you can use the crypto. Write a calculateHashWithNonce nonce: number function that will concatenate the provided nonce with an input string and will invoke generateHash.

Write a mine function that will invoke calculateHashWithNonce in a loop until the generated hash starts with We used the JavaScript keywords async and await, which are explained in the appendix. Read the code—you should be able to understand how it works. Try it with ten zeros, and the calculation may take hours.

Calculating the nonce is time-consuming, but verification is fast. To check if the program in listing 8. To make this method more useful, we could add an argument to it: mine difficulty: number : Promise The value of difficulty could be used to represent the number of zeros at the beginning of the hash value.

Increasing the difficulty would substantially increase the time required to find the nonce. The first app without the proof of work will create a blockchain and provide an API for adding blocks to it. Both programs will run from the command line using the node. You can define a command of any name and ask npm to run it by entering npm run command-name.

As per the content of the scripts section of our project, you can run the tsc compiler as follows: npm run tsc You may ask, why not just run the tsc command from the command line? You can do that if the tsc compiler is installed globally on the computer where you run it, and this may be the case if you run this command on your computer, where you have full control over the globally installed tools. Developing your first blockchain This may not be the case if your firm has a dedicated team responsible for building and deploying projects on their computers.

They may require you to provide the application code as well as the build utilities in one package. A type definition file in action We introduced type definition files in chapter 6. These files include type declarations for public JavaScript APIs, and in this project we use the file describing the Node.

If type definition files for a JavaScript library or module are present, IDEs can offer context-sensitive help. The following screenshot shows the VS Code editor after we entered the word crypto. The npmjs. Our project also includes the following tsconfig. While the outDir and target compiler options are self-explanatory, module and lib require additional explanation. Prior to ES6, JavaScript developers were using different syntax for splitting code into modules.

ES6 introduced the import and export keywords, so a script from one module could import whatever was exported from another. In TypeScript, we always use ES6 modules, and if a script needs to load some code from a module, we use the import keyword.

For example, to use code from the Node. As for lib, TypeScript comes with a set of libraries that describe APIs provided by browsers and JavaScript specs of different versions. You can selectively make these libraries available to your program via the lib compiler option.

It contains the classes Block and Blockchain as well as a short script that uses the API of Blockchain to create a blockchain of three blocks. The Block class declares the properties required for each block such as the index, and hash values of the current and previous blocks as well as the method to calculate its hash using the Node. During the instantiation of the Block object, we calculate its hash based on the concatenated values of all of its properties. This concatenated string is given to the crypto module, which calculates its hash in the form of a string of hexadecimal characters.

This hash is assigned to the hash property of the newly created Block object, which will be given to the Blockchain object to be added to the chain. In a real-world application, the data property would have a custom type that describes the structure of the data, but in our primitive blockchain, using the string type is fine.

The genesis block is created in the constructor of Blockchain. To run this script, compile it and run its bc The chain array stores three blocks of our primitive blockchain. Mining block It will be different for each reader. NOTE Notice that the previousHash of each block except the genesis block has the same value as the hash property of the previous block in the chain. This program runs very quickly, but a real-world blockchain would require data miners to spend some CPU cycles and solve an algorithm so that the generated hashes conform to certain requirements, as described in section 8.

This script has a lot of similarities to bc In particular, the Block class has a nonce property that is calculated in the new mine method. The nonce will be concatenated to other properties of the block to produce a hash that starts with five zeros. The process of calculating a nonce that meets our requirements will take some time.

This time, we want hashes that start with five zeros. The mine method will invoke calculateHash multiple times with different nonce values until the generated hash starts with The new version of the Block class is shown in the following listing. The only difference is that we append the value of the nonce to the input string used for calculating the hash. The mine method keeps calling calculateHash in a loop, providing the sequential numbers 0, 1, 2, … as the nonce argument.

Sooner or later, the calculated hash will start with , and the mine method will return the hash as well as the calculated nonce. The mine method returns the object with two properties, and we extract their values into two variables: nonce and hash. It may take several seconds to complete, as it spends time doing block mining.

The output of this script is shown in the following listing. Take another look at the code in listing 8. Each of the six class properties has a type and is marked as readonly. The properties nonce and hash were explicitly declared on this class, and four more properties were created by the Typescript compiler because we used the readonly qualifier with each argument of the constructor. Both class methods explicitly declare the types of their arguments and return values.

Both methods were declared with the private access level, which means that they can be invoked only within the class. In a blockchain, each block is identified by a hash value and is linked to the previous block by storing the hash value of the previous block. Before inserting a new block into the blockchain, a mathematical problem is offered to each node of the blockchain interested in calculating an acceptable hash value for a reward.

In our sample blockchain app, the acceptable hash value had to start with five zeros, and we calculated the nonce to ensure that the hash of the block indeed started with five zeros. Calculating such a nonce takes time, which delays the insertion of the new block into the blockchain, but it can be used as the proof of work needed to award the blockchain node that did it faster than others.

We launched that app from the command line, and it ran under the Node. Also, we created a small library that contains the code for mining blocks and generating the proper hash; this library can be used in a browser as well as in the Node. Figure 9. Compiled code is here. Project dependencies are installed here. The main machinery for creating the blockchain is implemented in the lib directory, but we provided two demo apps—one for the web browser and another for the Node.

It also has a universal function for generating hashes for both the browser and Node. This code uses the code in the lib directory. The copyfiles package will do this job. We started using npm scripts in section 8. Listing 9. The sources of this project are located in the src directory, and the deployed code will be saved in dist. Running the blockchain web app Note that this project has two tsconfig.

The base tsconfig. Also, we want to generate source map files that map the lines in the TypeScript code to the corresponding lines in the generated JavaScript. With source maps, you can debug your TypeScript code while you run the web app in the browser, even though the browser executes JavaScript.

The other tsconfig. This file inherits all the properties from the tsconfig. The child configuration file in the node directory overrides the module property with the value commonjs, so the TypeScript compiler will generate module-related code as per the CommonJS rules. TIP 9. The scripts section of package. The compileDeploy command runs two commands: tsc and deploy. One of the most popular bundlers is Webpack, which we introduced in section 6. NOTE Now you can start the web server by running the following command: npm start This command will start the web server on localhost on port The console will show the output you can see in figure 9.

However, custom scripts like compileDeploy require the run command. NOTE 9. The index. Enter the transaction here. Add the transaction to the pending ones. Pending transactions are shown here. The disabled Confirm Transactions button 5. The genesis block Figure 9.

The user can add transactions and click on the Transfer Money button after each transaction, which will add the transaction to the Pending Transactions field. This is what the Confirm Transactions button is for. In real-world apps, the account balance is checked first, and only afterwards is the pending transaction created. NOTE As in chapter 8, the new block, 1, was created with a hash value that starts with four zeros.

But now the block includes two transactions: one between John and Mary, and the other between Alex and Bill. The block has also been added to the blockchain. As you see, no pending transactions are left. The new block is added to the chain. John is buying an apartment from Mary and needs to provide proof that he paid for it.

Similarly, Alex is paying Bill for a house, and this is another transaction. While these transactions are in a pending state, they are not considered proof of payment. Home TypeScript Quickly. TypeScript Quickly. TypeScript Mcqs 1. TypeScript is used primaril 38 1 19KB Read more. TypeScript is a typed su 56 19 2MB Read more. Typescript Cheatsheet 88 13 60KB Read more. Which of the following is valid command to com 22 0 KB Read more.

This section is for adding transactions. The section of index. The latter is a compiled version of main. When the browser loads simple-websocket-client. Note that the protocol is ws and not http. To see this sample in action, run npm install and compile the code by running the custom command defined in package. The first one loads the simple-websocket-client.

Figure It denotes incoming socket messages. Up arrows mark messages sent by the client. The WebSocket object has a readyState property, which can have one of the values shown in table Table The connection is not yet open. If you keep looking at this table with its limited set of constants, sooner or later TypeScript enums will come to mind, right?

In the Frames panel, an arrow on the left pointing up means the message went up to the server. An arrow pointing down means that the message arrived from the server. If there were other nodes, the server would have broadcast the request to other nodes, collected their responses, and sent them to the original node-requestor—the client that requested the longest chain.

Note that we define custom types using the type, interface, and enum TypeScript keywords. Listing By comparing the correlation IDs of outgoing and incoming messages, we can find matching requests and responses. Since a UUID is a fixed size and contains a time field, it is possible for values to rollover around A.

Instead, we created a UUID type alias using the type keyword see listing We also import the http object from Node. The fragment '.. Server, we pass the instance of the existing HTTP server to it. Its code is located in the blockchain-server. The BlockchainServer class is a subclass of MessageServer, which encapsulates all the work related to WebSocket communications. The first part of the blockchain-server. GetLongestChainRequest : Invokes the return this. GetLongestChainResponse : handler based on return this.

NewBlockRequest : return this. NewBlockAnnouncement : return this. GetLongestChainResponse, clients. It has a switch statement to invoke the appropriate handler based on the received message. First it stores the request the reference to the open WebSocket object in a map using the correlation ID as a key. Then it broadcasts the message to other nodes, requesting their longest chains. The handleGetLongestChainRequest method can return an object with an empty payload only if the blockchain has just one node.

NOTE Listing It has the code that handles responses from other nodes sending their longest chains. Checks if there is more than one node in the blockchain When nodes send their GetLongestChainResponse messages, the server uses the correlation ID to find the client who requested the longest chain. When all nodes have replied, the handleGetLongestChainResponse method turns the allReplies set into an array and uses the reduce method to find the longest chain.

Then it sends the response back to the requesting client using the replyTo method. All this machinery is located in the abstract MessageServer superclass, shown in listings First of all, this class is declared as abstract see section 3.

In our case, the BlockchainServer subclass implements the only abstract member, handleMessage. Also, the class declaration uses the generic type T see section 4. In our app, the concrete type Message see listing By declaring the handleMessage method as abstract, we state that any subclass of MessageServer is free to implement this method any way it likes, as long as the signature of the method looks like this: protected abstract handleMessage sender: WebSocket, message: T : void; Because we enforced this method signature in the abstract class, we know how the handleMessage method should be invoked when implemented.

We do that in subscribeToMessages as follows: this. The following listing shows the second part of the MessageServer class. These methods implement broadcasting and replying to clients. This object has a clients property, which is a collection of all active WebSocket clients. Whenever we need to broadcast a message to all clients, we iterate through this collection as in the broadcastExcept method. If we need to remove a reference to a disconnected client, we also use the clients property in the cleanupDeadClients method.

The signatures of the broadcastExcept and replyTo methods have an argument of a Readonly mapped type, which we covered in section 5. It takes a T type and marks all of its properties as readonly. We use the Readonly to avoid accidental modifications being made to the value within the method.

The second client joins the blockchain and sends a message to the WebSocket server requesting the longest chain, which is just the genesis block at the moment. The server broadcasts this request to other clients. The first client on the left receives this request. This client has a single genesis block, which is its longest chain. The first client on the left sends a message back with its longest chain in the message payload.

The second client on the right receives the longest chain in the message payload. In this example, we have only two clients, but the WebSocket server broadcasts the messages to all connected clients, so all of them would respond. Next, the first client on the left in figure This is a local event and no messages are being sent to the WebSocket server. Received longest chain request 3. Responded to 1. Requesting longest chain longest chain request The second client 4.

Longest chain received Figure An invite to mine Announcing a candidate block Figure Note that the hash value of block 0 and the previousHash value of block 1 are the same. We shortened the hash values to improve readability. The next question is: Who sent the message with the payload containing the newly mined block? Debugging Node. That octagon represents the Node. By default, the Node.

Switch to the Sources tab, as shown in the following figure, find the TypeScript code that you want to debug, and add a breakpoint. The following image shows a breakpoint on line 9 in the blockchain-server. Reviewing notification workflows The line with a breakpoint The Sources tab Selecting the Sources tab We want to intercept the moment when the client sends a message to the server.

The line with a breakpoint Debugging Node. We added the message variable to the Watch panel at the top right, and we can debug or monitor this variable. The main subject of this chapter is introducing the messaging server. For HTML rendering we use a small library called lit-html www. The lit-html library efficiently renders the content from string templates to the DOM by updating only those nodes that need to display updated values.

It just updates the variable values. The first fragment of the application. After several seconds, the second rendering is done from the initializeBlockchain method. Child UI components get the reference to the requestRendering callback, and they can decide when to refresh the UI. The initializeBlockchain method is invoked after the initial rendering of the UI, and this method requests the longest chain from the WebSocket server.

If this node is not the first and only one, the longest chain is returned and is rendered in the block panel at the bottom of the screen. Otherwise the genesis block is generated and rendered. Both requestLongestChain and initializeWithGenesisBlock are asynchronous operations, and the code waits for their completion by using the await JavaScript keyword. The handleServerMessages method is invoked when the WebSocket server sends a message to the client.

Using the switch statement, it invokes the appropriate handler based on the message type. The handleGetLongestChainRequest method is invoked when the client receives a request to send its longest chain. GetLongestChainRequest: return this. GetLongestChainResponse, correlationId: message. Prior to version 3. The interface defines a custom Block type with five properties, and all of them are required and readonly, meaning they can be initialized only during the instantiation of the block.

But creating a block takes some time, and not all the values for these properties are available during instantiation. TypeScript comes with a Pick mapped type and a conditional Exclude type, and we can use them to define a new type that excludes some of the properties of existing ones.

Exclude enumerates the remaining properties. The Pick type allows you to create a type from the provided list of properties. For example, if we provide Block as type T, the keyof T construct will represent the list of properties defined in the Block interface.

Using Exclude allows us to remove some of the properties from the list, and Pick will create a new type from that new list of properties. Mine the block. In listing Then this node starts mining as well. It may exist, but not in the last block. The second if statement checks if there is at least one block after the one that contains this previousHash.

This would mean that at least one new block has already been added to the chain received from other nodes. In this case, the longest chain takes precedence and the newly generated block is rejected. The Application class also has a handleServerMessages method, which handles messages arriving from the server. The Application class creates an instance of WebsocketController, which is our only contact for all communications with the server.

The connect method connects to the server and subscribes to the standard WebSocket messages. These actions are wrapped in a Promise, so if this method returns, we can be sure that the WebSocket connection is established and all handlers are Reviewing notification workflows assigned. An additional benefit is that now we can use the async and await keywords with these asynchronous functions. In that method, we deserialize the message and check its correlation ID.

If the incoming message is a response to another message, the following code will return true: messagesAwaitingReply. The PromiseExecutor knows which client waits for the response. Promises may have various constructor signatures; for example, all of them have then , but they may or may not have catch. In such scenarios, a JavaScript caller can create a Promise, providing the resolve and reject callbacks as explained in section A. For messages expecting replies, we need a way to push the reply when it arrives.

We could use a Promise, which could be resolved or rejected using the callbacks that we pass to the constructor as Promise resolve, reject. In other words, PromiseExecutor is just a container for two callbacks.

When the response arrives, the onMessageReceived method finds the PromiseExecutor object by the correlation ID, it invokes resolve , and it deletes this message from the map: this. The following listing shows how the client can request the longest chain. The WebsocketController class has several other methods that deal with other types of messages.

They are implemented much like requestLongestChain. To see this app in action, run npm install and then npm start. Open a couple of browser windows and try to mine some blocks. The longest chain rule can help to find the winning node and reach a consensus amongst nodes. Each project will have its own package. Whereas HTTP is a request-based protocol, WebSocket is not, which makes it a good choice when a server needs to push data to a client. In particular, AtScript would support decorators, which were not in TypeScript back then.

Then one of the Googlers suggested meeting with the TypeScript team from Microsoft to see if they would be willing to add decorators to TypeScript itself. The Microsoft folks agreed, and the Angular 2 framework was written in TypeScript, which also became a recommended language for developing Angular apps.

This chapter will provide a brief introduction to the Angular framework. Chapter 12 contains a code review of the blockchain app written in Angular. Today, the main players in the market for developing web apps besides the superpopular jQuery are Angular and React. Angular is a framework, whereas React. Chapter 13 will get you started with developing web apps using React. Chapter 15 will cover the basics of Vue.

The difference between a framework and library is that a framework forces you to write your apps in a certain way, whereas a library offers you certain features that you can use in any way you like. This command can be used for generating a new workspace, application, library, component, service, and more.

To get help for a specific parameter, run ng help followed by the name of the parameter you need help with, such as ng help new. In this chapter, we used Angular CLI 7. To see which version is installed on your computer, run ng version. To generate a new minimalistic project, run the ng new command followed by the name of the project a. In the next 30 seconds, it will run npm and install all required dependencies. The file with dependencies Figure It will produce the console output shown in figure At the time of writing, the ng serve command uses Webpack to bundle your apps and Webpack DevServer to serve it.

By default, your app is served at localhost The app bundle Figure The app code is located in the main. Running the production build, ng serve --prod, would produce bundles with a total size of just over KB. First, terminate the running helloworld app by pressing Ctrl-C in the terminal window. Next, open the helloworld directory in VS Code, which offers a lot more convenient development environment than a terminal window and a plain text editor.

All these files were generated by Angular CLI. The source code of our app is located in the src folder, and at the very minimum it will have one component app. The content of app. Take my word for it! The other way to do this is by using the props property of the Component decorator.

For example, the child component can send a place-order event with orderData as the payload to the parent as follows: this. There, the PendingTransactionsPanel component sends the generate-block event to its parent. The first app is located in the router-product-list directory and the second is in router-product-details. In chapter 11, we introduced the Angular router. The vue-router package implements client-side navigation using similar concepts.

The user will be able to click on the selected product so the app can process it as needed. The About link will navigate to the About view without making any requests to the server. It creates a bookmarkable location that can be shared and opened directly without the need to go through multiple steps to see a desired view. Also, the router allows you to avoid loading separate web pages from the server— the page remains the same, but the user can navigate on the client from one view to another without asking the server to load a different page.

This is possible because the code of all UI components is already downloaded by the browser. A framework that supports client-side routing produces anchor tags that include click handlers to invoke functions on the client and update the address bar. If the user clicks the About link for the first time, Vue will lazily load the About component before rendering it. For all subsequent clicks on this link, only the About component will be rendered. Developing single-page apps with router support The CLI also asked if this app should use the history mode for router, and we agreed to this.

Without history mode, all the URLs in your app will include hash sign to separate the server and client portions of the URL. The URL segment to the right of the hash sign is handled by the client app. Change to the router-product-list directory and run the command npm run serve. It will look similar to figure These components are controlled by the Vue Router. Note the URL in figure There is no client segment in this URL. If the user clicks on the About link, the browser renders the About component, as shown in figure The generated main.

TIP The Vue instance includes a reference to the Router object that contains configured routes, so it knows which component to render if the user clicks on Home or About. The initial routes configuration was generated in the router. In the following listing, this array is called routes. Note the mode property: its value is history because we selected history mode during app generation. For this to happen, the code instructs Webpack that when it generates production bundles, that it should split the code and generate a separate chunk about.

The import is done dynamically only if the user decides to navigate to the About view. TIP To see that Webpack does split the code, run the production build with npm run build and check the content of the dist directory. Our top-level component, App. The tag defines the area where the changing content the Home or About component will be rendered.

Each has a to attribute, telling Vue which component to render based on the configured routes. You can bind a variable to the :to attribute note the colon in front of to. We used MakeTypes to generate the Product interface, which is located in the product. Our app should read this file as soon as the user navigates to the Home route, which is the default route.

But where in the Home component should we put the code for fetching data? Do we know exactly when the creation of the Home component is complete? Yes, we do. In the TypeScript file-declarations file, options. It contains the declarations of all the life cycle hooks.

Life cycle hooks are invoked by Vue, so we just need to put our data-fetching code inside the created method. The following listing shows the first modified version of the Home component. This is possible because the tsconfig. For example, instead of writing you can write. For people who write JavaScript! Download a free PDF sample 3. About the book. The book is packed with many real world examples and great tips, transforming you into a TypeScript expert by the end of it.

Highly recommended read! According to several developer surveys, TypeScript is one of the most loved programming languages. But the sheer amount of material, perspectives, and use cases can be overwhelming. I was no exception. Oh, how wrong I was! TypeScript can be much more than that — a subtle tool, a simple layer atop JavaScript, the programming language that drives the web.

TypeScript in 50 lessons will give you a gentle, human introduction to TypeScript. Right around the midpoint, we take the leap into structural type systems and why they are so great and useful for JavaScript. TypeScript in 50 lessons is a very practical book. It features lots of examples that not only give you an idea about syntax and semantics, but show you actual use-cases that you might encounter in your applications.

To help you follow the code examples in the book, I set up projects on Code Sandbox and the TypeScript playground, where you can fiddle around on your own and see how TypeScript's type system behaves. The links open online editors that serve as a starting point for you to follow the contents of the book.

We go on a hunt for red squiggly lines. In this opening chapter, we will see that — given the right tools — we might already be using TypeScript without realizing. With TypeScript being a gradual type system, we can gently encourage the programming language to give us more insights into our code.

We will also write our first types. We learn about some major features of TypeScript, like type annotations, type inference, and control flow. We will define primitive and complex types, and learn about the difference between types and interfaces.

For every variable or constant we can create, we find a way to provide a type. Functions are an essential feature in JavaScript, and we can see that once we want to type function signatures. We learn about function heads and bodies, structural typing for functions, and how we can define different behavior for the same function. This allows for algebraic operations like union and intersections, making it a lot easier for us to define concrete types for values.

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TypeScript Tutorial #2 - Compiling TypeScript

I've been looking at the issues that turn up commonly when people start using TypeScript.

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Typescript ebook torrent Imagine a server that has information about the available seats on some airlines. In contrast, a hashing utility uses a unidirectional function. To help you follow the code examples in the book, I set up projects on Code Sandbox and the TypeScript playground, where you can fiddle around on your own and see how TypeScript's type system behaves. You can bind a variable to the typescript ebook torrent attribute note the colon in front of to. Vue comes with a number of directives that tell the Vue instance what to do with the DOM element. What if their code changes, breaking your app?
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