Continous Typescript “transpilation” with Grunt

I think Typescript is really a very good tool to develop good Javascript. I also think that Typescript can make you love Javascript. Of course, you can use Visual Studio on Windows, but you can also use Typescript with Linux or OSX (like me). We’ll see how to do “Continuous Typescript Transpilation” thanks to Grunt (plus it also works under windows). I find it even more convenient with Visual Studio.

And it’s very simple.

You can use your favorite text editor : you can find syntax highlighting support for SublimeText, Vim and Emacs here :

First Tools

First Project

Create your main directory project with sub-directories like that :

myapp-| |-ts\ <– typescript files here + grunt.js |-app-\ <– javascript files here


In ts directory, create a grunt.js file with this content :

module.exports = function(grunt) {



	    typescript: {
	      base: {
	        src: ['*.ts'],
	        dest: '../app',
	        options: {
	          target: 'es5' //or es3

		  watch: {
		    files: '**/*.ts',
		    tasks: ['typescript']


	grunt.registerTask('default', 'watch');

If you launch grunt in ts directory (from a terminal), typescript files will be compiled to javascript whenever you save your changes.

Try it

  • Open a terminal
  • Go to myapp/ts
  • run (type) command grunt (under Windows, type grunt.cmd)
  • create a new typescript file human.ts in ts directory with this content :

      class Human {
          constructor (
              public firstName: string = "John", 
              public lastName: string = "Doe") {
              console.log("Hello ", firstName, lastName);
  • save it
  • human.ts is transpiled to app/human.js :

      var Human = (function () {
          function Human(firstName, lastName) {
              if (typeof firstName === "undefined") { firstName = "John"; }
              if (typeof lastName === "undefined") { lastName = "Doe"; }
              this.firstName = firstName;
              this.lastName = lastName;
              console.log("Hello ", firstName, lastName);
          return Human;
  • and human.ts will be transpiled, each time you save your changes. Compilation errors are displayed in the terminal.
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