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September 4, 2015

Use TypeScript to Prepare for Angular 2

If you are developing now in Angular 1.x with an eye toward Angular 2, the best thing you can do is to write your Angular code with TypeScript. Angular 1.x code you write in TypeScript today will look very similar to code you will write in Angular 2 tomorrow (not literally tomorrow!).

At a recent Angular conference, the members of the Angular team from Google stated that one of the best ways to code now in Angular 1.x in preparation for Angular 2 is to use TypeScript.

What is TypeScript?

image

TypeScript is an open-source programming language that is:

  • A superset of JavaScript
    • Including all of the current JavaScript syntax, plus much more.
    • Any valid JavaScript code is valid TypeScript code. And as such, TypeScript works with all existing JavaScript frameworks, including Angular.
  • TypeScript transpiles to plain JavaScript
    • So we can deploy the resulting JavaScript files for our Angular application just as we do now.
    • And the resulting files execute in any of today’s browsers on any OS.
    • Plus there is no runtime overhead of using TypeScript because all of the types evaporate and the TypeScript-only syntax is replaced … leaving only pure JavaScript.
  • TypeScript allows us to define strong types
    • Editor tooling, such as the new Visual Studio Code editor, use these types for static type checking of our code during development
    • This makes development, debugging, and refactoring easier.
    • Plus it clarifies the developer’s intent. For example, we can define that a function is meant to take in a string. Not a number, not an object, just a string.
  • And TypeScript provides class-based object-oriented programming techniques.
    • So we can optionally think of our code in terms of objects with properties and methods.
    • And the TypeScript compiler transpiles the classes into JavaScript functions.

Here is the code for an Angular controller, written using the class-based object-oriented programming techniques available in TypeScript.

AngularWTypeScript_Code

To learn more about using Angular with TypeScript, check out the Pluralsight course: “Angular with TypeScript

AngularWTypeScript

Enjoy!

August 12, 2015

Automatic Compilation in VS Code for TypeScript

Filed under: TypeScript,VS Code @ 2:19 pm
Tags: ,

By default, when you use VS Code with a TypeScript project, you need to use Ctrl+Shift+B (or Cmd+Shift+B on a mac) to build the application and transpile the TypeScript to JavaScript. But there is a way to make this process more seamless.

To set up VS Code to watch for changes and transpile automatically requires two steps:

1) Modify the tsconfig.json file for the project.

2) Run the TypeScript compiler on the folder for the project.

Let’s look at both of these steps in detail.

Modify the tsconfig.json File

The tsconfig.json file configures TypeScript for your project. In the tsconfig.json file you can define compiler options, such as the version of JavaScript you’d like the transpiler to use. The TypeScript code is then transpiled to the selected version of TypeScript.

To configure VS Code for automatic compilation, you need to add a watch property here:

{
    “compilerOptions”: {
        “target”: “ES5”,
       “watch”: true
    }
}

NOTE: The intellisense does not seem to know about the “watch” option. So you won’t see it in the list of available compiler options. But it does work.

Run the TypeScript Compiler

You can manually run the TypeScript compiler from within VS Code by using Ctrl+Shift+B (or Cmd+Shift+B). Alternatively, you can manually run the TypeScript compiler from the command window (also called a terminal).

1) Right-click on the index.html file in the VS Code Explore pane and select Open in Console.

This opens a command window defaulted to the current project directory.

2) Type tsc.

Typing tsc (for TypeScript compiler) immediately transpiles all of the TypeScript code in the directory (and subdirectories) to JavaScript. Without the “watch” setting, if you later make changes to the TypeScript code, you have to re-run the tsc command to transpile the changes.

image

HOWEVER, if you have the watch compiler option set to true as shown in the code example above, running tsc here produces a different result. In this case, the TypeScript compiler will immediately transpile all of the TypeScript code in the directory (and subdirectories). But then, it will start watching for changes. Any change it sees to the files in the directory will automatically be transpiled. Notice in the screen shot below that it watched me make 3 changes and compiled after each of them.

image

If you leverage VS Code’s AutoSave feature, and turn on the watch following the two steps detailed above, then the TypeScript compiler will transpile your TypeScript files every time you make a change.

Enjoy!

For more information on other techniques when building an Angular application with TypeScript, check out my Pluralsight course: “Angular with TypeScript”

Thanks to Greg who posted this suggestion to the Discussion forum for my Pluralsight course.

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