Re-export to extend Often you will need to extend functionality on a module. A common JS pattern is to augment the original object with extensions, similar to how JQuery extensions work. As we’ve mentioned before, modules do not merge like global namespace objects would. The recommended solution is to not mutate the original object, but rather export a new entity that provides the new functionality. Consider a simple calculator implementation defined in module Calculator.ts. The module also exp

Module Resolution Strategies There are two possible module resolution strategies: Node and Classic. You can use the --moduleResolution flag to specify the module resolution strategy. The default if not specified is Node.

Debug In Edge, press F12 and click the Debugger tab. Look in the first localhost folder, then src/app.ts Put a breakpoint on the line with return. Type in the boxes and confirm that the breakpoint hits in TypeScript code and that inspection works correctly. That’s all you need to know to include basic TypeScript in your ASP.NET project. Next we’ll include Angular and write a simple Angular app.

Add TypeScript The next step is to add a folder for TypeScript. We’ll just call it scripts.

this Learning how to use this in JavaScript is something of a rite of passage. Since TypeScript is a superset of JavaScript, TypeScript developers also need to learn how to use this and how to spot when it’s not being used correctly. Fortunately, TypeScript lets you catch incorrect uses of this with a couple of techniques. If you need to learn how this works in JavaScript, though, first read Yehuda Katz’s Understanding JavaScript Function Invocation and “this”. Yehuda’s article explains the in

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“Do”s and “Don’t”s Many common mistakes in declaration files can be easily avoided. The Do’s and Don’ts section identifies common errors, describes how to detect them, and how to fix them. Everyone should read this section to help themselves avoid common mistakes.

async/await support in ES6 targets (Node v4+) TypeScript now supports asynchronous functions for engines that have native support for ES6 generators, e.g. Node v4 and above. Asynchronous functions are prefixed with the async keyword; await suspends the execution until an asynchronous function return promise is fulfilled and unwraps the value from the Promise returned. Example In the following example, each input element will be printed out one at a time with a 400ms delay: "use strict"; // pr

Iterables An object is deemed iterable if it has an implementation for the Symbol.iterator property. Some built-in types like Array, Map, Set, String, Int32Array, Uint32Array, etc. have their Symbol.iterator property already implemented. Symbol.iterator function on an object is responsible for returning the list of values to iterate on.

Putting it all together Just run: webpack Now open up index.html in your favorite browser and everything should be ready to use! You should see a page that says “Hello from TypeScript and React!”