TypeScript Compiler Configuration

TypeScript compiler uses tsconfig.json to get configuration options for generating JavaScript code from TypeScript source-code. When you uses '$ tsc' command to compile TypeScript code, compiler searches for configurations located in tsconfig.json.

1. The tsconfig.json is generally put in the root folder of the project.
2. It provides the compiler options required to compile the project.

1. Creating tsconfig.json

Before we start using TypeScript, make sure we have installed it. To use conveniently, install it as global dependency so that we can use tsc command from console window.

Then use 'tsc --init' command to create tsconfig.json file in your project’s root folder.

$ npm install typescript -g 	//Install typescript

$ cd project_root		//Go to project's root folder

$ tsc --init			//Create tsconfig.json in project's root folder

A default tsconfig.json will be created.

{ 
   "compilerOptions":{ 
      "target":"es6",
      "moduleResolution":"node",
      "module":"commonjs",
      "declaration":false,
      "noLib":false,
      "emitDecoratorMetadata":true,
      "experimentalDecorators":true,
      "sourceMap":true,
      "pretty":true,
      "allowUnreachableCode":true,
      "allowUnusedLabels":true,
      "noImplicitAny":true,
      "noImplicitReturns":false,
      "noImplicitUseStrict":false,
      "outDir":"dist/",
      "baseUrl":"src/",
      "listFiles":false,
      "noEmitHelpers":true
   },
   "include":[ 
      "src/**/*"
   ],
   "exclude":[ 
      "node_modules"
   ],
   "compileOnSave":false
}

2. TypeScript Compiler Options

Let’s go through some important compiler options, we must know.

OptionDescription
allowJsAllow JavaScript files to be compiled. Default value is false.
alwaysStrictParse in strict mode and emit “use strict” for each source file. Default value is false.
moduleThe output module type e.g. “CommonJS”, “AMD“, “System“, “ES6“, “ES2015” or “ESNext“.
Default value is CommonJS if target attribute is ES3 or ES5; else default is ES6.
targetSpecify ECMAScript target version. Default value is ES3.
moduleResolutionDetermine how modules get resolved. For module type ES6, AMD or System – default value is classic; else Node.
sourceMapIndicates to generate sourcemap or not. Sourcemaps helps in debugging.
outDirThe location in which the transpiled files should be kept.
baseUrl or pathsInstructing TypeScript where it can find the type files.
watchUsed for livereload. It means that whenever any of the source file is changed, then the compiling process is re-triggered to generate the transpiled files again.
experimentalDecoratorsThis option enables using decorators in TypeScript projects. ES has not yet introduced decorators, so they are disabled by default.

Follow official page for complete list of compiler options.

3. Include and exclude options

These options takes an array of global patterns that need to be included in the compilation path, to add or remove files from compilation process.

"include":[ 
  "src/**/*",
  "src/app/shared/**/*",
  "typings/*.d.ts"
],
"exclude":[ 
  	"node_modules",
	 "jspm_packages",
	 "application", 
	 "system",
	 "dist"
]

Drop me your questions in comments section.

Happy Learning !!

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2 thoughts on “TypeScript Compiler Configuration”

  1. Typo on the typescript install:

    $ npm uninstall typescript -g   //Install typescript
    

    should be

    $ npm install typescript -g   //Install typescript
    
    Reply

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