angular-cli/packages/@angular/cli/commands/doc.ts

import { Command } from '../models/command';
import opn from 'opn';

export interface Options {
  keyword: string;
  search?: boolean;
}

export default class DocCommand extends Command {
  public readonly name = 'doc';
  public readonly description = 'Opens the official Angular API documentation for a given keyword.';
  public static aliases = ['d'];
  public readonly arguments = ['keyword'];
  public readonly options = [
    {
      name: 'search',
      aliases: ['s'],
      type: Boolean,
      default: false,
      description: 'Search whole angular.io instead of just api.'
    }
  ];

  public validate(options: Options) {
    if (!options.keyword) {
      this.logger.error(`keyword argument is required.`);
      return false;
    }
  }

  public async run(options: Options) {
    let searchUrl = `https://angular.io/api?query=${options.keyword}`;
    if (options.search) {
      searchUrl = `https://www.google.com/search?q=site%3Aangular.io+${options.keyword}`;
    }

    return opn(searchUrl, { wait: false });
  }
}