@angular-devkit/build-optimizer

Angular Build Optimizer

Angular Build Optimizer contains Angular optimizations applicable to JavaScript code as a TypeScript transform pipeline.

This package is deprecated and should not be used. It has always been experimental (never hit 1.0.0) and was an internal package for the Angular CLI. All the relevant functionality has been moved into @angular-devkit/build-angular.

Available optimizations

Transformations applied depend on file content:

• Class fold, Scrub file and Prefix functions: applied to Angular apps and libraries.
• Import tslib: applied when TypeScript helpers are found.

Some of these optimizations add /*@__PURE__*/ comments. These are used by JS optimization tools to identify pure functions that can potentially be dropped.

Class fold

Static properties are folded into ES5 classes:

// input
var Clazz = (function () {
  function Clazz() {}
  return Clazz;
})();
Clazz.prop = 1;

// output
var Clazz = (function () {
  function Clazz() {}
  Clazz.prop = 1;
  return Clazz;
})();

Scrub file

Angular decorators, property decorators and constructor parameters are removed, while leaving non-Angular ones intact.

// input
import { Injectable, Input, Component } from '@angular/core';
import { NotInjectable, NotComponent, NotInput } from 'another-lib';
var Clazz = (function () {
  function Clazz() {}
  return Clazz;
})();
Clazz.decorators = [{ type: Injectable }, { type: NotInjectable }];
Clazz.propDecorators = { 'ngIf': [{ type: Input }] };
Clazz.ctorParameters = function () {
  return [{ type: Injector }];
};
var ComponentClazz = (function () {
  function ComponentClazz() {}
  __decorate([Input(), __metadata('design:type', Object)], Clazz.prototype, 'selected', void 0);
  __decorate(
    [NotInput(), __metadata('design:type', Object)],
    Clazz.prototype,
    'notSelected',
    void 0,
  );
  ComponentClazz = __decorate(
    [
      NotComponent(),
      Component({
        selector: 'app-root',
        templateUrl: './app.component.html',
        styleUrls: ['./app.component.css'],
      }),
    ],
    ComponentClazz,
  );
  return ComponentClazz;
})();

// output
import { Injectable, Input, Component } from '@angular/core';
import { NotInjectable, NotComponent } from 'another-lib';
var Clazz = (function () {
  function Clazz() {}
  return Clazz;
})();
Clazz.decorators = [{ type: NotInjectable }];
var ComponentClazz = (function () {
  function ComponentClazz() {}
  __decorate(
    [NotInput(), __metadata('design:type', Object)],
    Clazz.prototype,
    'notSelected',
    void 0,
  );
  ComponentClazz = __decorate([NotComponent()], ComponentClazz);
  return ComponentClazz;
})();

Prefix functions

Adds /*@__PURE__*/ comments to top level downleveled class declarations and instantiation.

Warning: this transform assumes the file is a pure module. It should not be used with unpure modules.

// input
var Clazz = (function () {
  function Clazz() {}
  return Clazz;
})();
var newClazz = new Clazz();
var newClazzTwo = Clazz();

// output
var Clazz = /*@__PURE__*/ (function () {
  function Clazz() {}
  return Clazz;
})();
var newClazz = /*@__PURE__*/ new Clazz();
var newClazzTwo = /*@__PURE__*/ Clazz();

Prefix Classes

Adds /*@__PURE__*/ to downleveled TypeScript classes.

// input
var ReplayEvent = (function () {
  function ReplayEvent(time, value) {
    this.time = time;
    this.value = value;
  }
  return ReplayEvent;
})();

// output
var ReplayEvent = /*@__PURE__*/ (function () {
  function ReplayEvent(time, value) {
    this.time = time;
    this.value = value;
  }
  return ReplayEvent;
})();

Import tslib

TypeScript helpers (__extends/__decorate/__metadata/__param) are replaced with tslib imports whenever found.

// input
var __extends =
  (this && this.__extends) ||
  function (d, b) {
    for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
    function __() {
      this.constructor = d;
    }
    d.prototype = b === null ? Object.create(b) : ((__.prototype = b.prototype), new __());
  };

// output
import { __extends } from 'tslib';

Wrap enums

Wrap downleveled TypeScript enums in a function, and adds /*@__PURE__*/ comment.

// input
var ChangeDetectionStrategy;
(function (ChangeDetectionStrategy) {
  ChangeDetectionStrategy[(ChangeDetectionStrategy['OnPush'] = 0)] = 'OnPush';
  ChangeDetectionStrategy[(ChangeDetectionStrategy['Default'] = 1)] = 'Default';
})(ChangeDetectionStrategy || (ChangeDetectionStrategy = {}));

// output
var ChangeDetectionStrategy = /*@__PURE__*/ (function () {
  var ChangeDetectionStrategy = {};
  ChangeDetectionStrategy[(ChangeDetectionStrategy['OnPush'] = 0)] = 'OnPush';
  ChangeDetectionStrategy[(ChangeDetectionStrategy['Default'] = 1)] = 'Default';
  return ChangeDetectionStrategy;
})();

Library Usage

import { buildOptimizer } from '@angular-devkit/build-optimizer';

const transpiledContent = buildOptimizer({ content: input }).content;

Available options:

export interface BuildOptimizerOptions {
  content?: string;
  inputFilePath?: string;
  outputFilePath?: string;
  emitSourceMap?: boolean;
  strict?: boolean;
  isSideEffectFree?: boolean;
}

Webpack loader usage:

import { BuildOptimizerWebpackPlugin } from '@angular-devkit/build-optimizer';

module.exports = {
  plugins: [
    new BuildOptimizerWebpackPlugin(),
  ]
  module: {
    rules: [
      {
        test: /\.js$/,
        loader: '@angular-devkit/build-optimizer/webpack-loader',
        options: {
          sourceMap: false
        }
      }
    ]
  }
}

CLI usage

build-optimizer input.js
build-optimizer input.js output.js

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