隨着前端框架的誕生，也會隨之出現一些組件庫，方便日常業務開發。今天就聊聊 angular4 組件庫開發流程。

下圖是 button 組件的基礎文件。

nk-button.component.ts 為該組件的核心文件，看看代碼：

import {Component, Renderer2, ElementRef, AfterContentInit, ViewEncapsulation, Input} from '@angular/core';

@Component({
  selector: '[nk-button]',
  templateUrl: './nk-button.component.html',
  encapsulation: ViewEncapsulation.None,
  styleUrls: ['./nk-button.component.scss']
})
export class NkButtonComponent implements AfterContentInit {
  _el: HTMLElement;
  _prefixCls = 'ky-btn';
  _type: string;
  _size: string;
  _shape: string;
  _classList: Array<string> = [];

  @Input()
  get nkType() {
    return this._type;
  }

  set nkType(value) {
    this._type = value;
    this._setClass();
  }

  @Input()
  get nkSize() {
    return this._size;
  }

  set nkSize(value: string) {
    this._size = value;
    this._setClass();
  }

  @Input()
  get nkShape() {
    return this._shape;
  }

  set nkShape(value: string) {
    this._shape = value;
    this._setClass();
  }

  constructor(private _elementRef: ElementRef, private _renderer: Renderer2) {
    this._el = this._elementRef.nativeElement;
    this._renderer.addClass(this._el, this._prefixCls);
  }

  ngAfterContentInit() {
  }

  /**
   *設置class屬性
   */
  _setClass(): void {
    this._classList = [
      this.nkType && `${this._prefixCls}-${this.nkType}`,
      this.nkSize && `${this._prefixCls}-${this.nkSize}`,
      this.nkShape && `${this._prefixCls}-${this.nkShape}`
    ].filter(item => {
      return item;
    });
    this._classList.forEach(_className => {
      this._renderer.addClass(this._el, _className);
    });
  }
}

針對核心概念 ElementRef、Renderer2、ViewEncapsulation 做簡要説明：

ElementRef

在應用層直接操作 DOM，就會造成應用層與渲染層之間強耦合，通過 ElementRef 我們就可以封裝不同平台下視圖層中的 native 元素 (在瀏覽器環境中，native 元素通常是指 DOM 元素)，最後藉助於 Angular 提供的強大的依賴注入特性，我們就可以輕鬆地訪問到 native 元素。

參考鏈接

Renderer2

渲染器是 Angular 為我們提供的一種內置服務，用於執行 UI 渲染操作。在瀏覽器中，渲染是將模型映射到視圖的過程。模型的值可以是 JavaScript 中的原始數據類型、對象、數組或其它的數據對象。然而視圖可以是頁面中的段落、表單、按鈕等其他元素，這些頁面元素內部使用 DOM 來表示。

參考鏈接

ViewEncapsulation

ViewEncapsulation 允許設置三個可選的值：

• ViewEncapsulation.Emulated - 無 Shadow DOM，但是通過 Angular 提供的樣式包裝機制來封裝組件，使得組件的樣式不受外部影響。這是 Angular 的默認設置。
• ViewEncapsulation.Native - 使用原生的 Shadow DOM 特性
• ViewEncapsulation.None - 無 Shadow DOM，並且也無樣式包裝

參考鏈接

button 組件創建思路：

• 針對 button 我們只需修改其樣式，因此在這裏創建屬性指令
• 提供屬性接口
• 根據其傳入的屬性值動態渲染 DOM

至此，最簡單的 button 就開發結束。

模塊打包流程

合併 html、css 到 component 文件

let fs = require("fs");
let pathUtil = require("path");
let sass = require("node-sass");
let filePath = pathUtil.join(__dirname, "src", "temp_components");

let fileArray = [];

function fildFile(path) {
  if (fs.statSync(path).isFile()) {
    if (/\.component.ts/.test(path)) {
      fileArray[0] = path;
    }
    if (/\.html$/.test(path)) {
      fileArray[1] = readFile(path);
    }
    if (/\.component.scss$/.test(path)) {
      fileArray[2] = path;
    }
  } else if (fs.statSync(path).isDirectory()) {
    let paths = fs.readdirSync(path);

    if (fileArray.length === 3) {
      writeFile(fileArray);
      fileArray = [];
    }
    paths.forEach((p) => {
      fildFile(pathUtil.join(path, p));
    });
  }
}

function readFile(file) {
  return fs.readFileSync(file);
}

function writeFile(fileArray) {
  let file = fileArray[0];
  let content = fileArray[1];
  let scssPath = fileArray[2];
  mergeContent(file, content, scssPath).then((result) => {
    if (!result) return;
    fs.writeFile(file, result, function (err) {
      if (err) console.error(err);
      console.log("file merge success!");
    });
  });
}

/**
 * 轉換scss
 * @param path
 * @returns {Promise}
 */
function processScss(path) {
  return new Promise((resolve, reject) => {
    sass.render(
      {
        file: path,
      },
      (err, result) => {
        if (!err) {
          resolve(result.css.toString());
        } else {
          reject(err);
        }
      }
    );
  });
}

function mergeContent(file, content, scssPath) {
  let componentContent = readFile(file);
  let htmlRegex = /(templateUrl *:\s*[\"|\'])(.*[\"|\']\,?)/g;
  let scssRegex = /(styleUrls *:\s*)(\[.*\]\,?)/g;

  let newContent = "";
  if (htmlRegex.test(componentContent) && scssRegex.test(componentContent)) {
    let contentArray = componentContent.toString().split(htmlRegex);
    contentArray[1] = "template:`";
    contentArray[2] = content + "`,";
    contentArray.forEach((con) => {
      newContent += con;
    });
    contentArray = newContent.toString().split(scssRegex);

    return new Promise((resolve, reject) => {
      processScss(scssPath).then(
        (result) => {
          newContent = "";
          contentArray[1] = "styles:[`";
          contentArray[2] = result + "`],";
          contentArray.forEach((con) => {
            newContent += con;
          });
          resolve(newContent);
        },
        (err) => {
          reject(err);
        }
      );
    });
  }
}

fildFile(filePath);

ts 編譯(tsconfig-aot.json)

{
  "extends": "./tsconfig.json",
  "compilerOptions": {
    "outDir": "./publish/src",
    "baseUrl": "./",
    "declaration": true,
    "importHelpers": true,
    "module": "es2015",
    "sourceMap": false,
    "target": "es2015",
    "types": [
      "node"
    ]
  },
  "files": [
    "./src/temp_components/ng-kylin.module.ts"
  ],
  "angularCompilerOptions": {
    "annotateForClosureCompiler": true,
    "strictMetadataEmit": true,
    "flatModuleOutFile": "index.js",
    "flatModuleId": "ng-kylin",
    "skipTemplateCodegen": true
  }
}

rollup 打包 (rollup-config.js)

import resolve from "rollup-plugin-node-resolve";
import replace from "rollup-plugin-replace";

const format = process.env.ROLLUP_FORMAT || "es";

let globals = {
  "@angular/animations": "ng.animations",
  "@angular/cdk": "ng.cdk",
  "@angular/core": "ng.core",
  "@angular/common": "ng.common",
  "@angular/compiler": "ng.compiler",
  "@angular/forms": "ng.forms",
  "@angular/platform-browser": "ng.platformBrowser",
  moment: "moment",
  "moment/locale/zh-cn": null,
  "rxjs/BehaviorSubject": "Rx",
  "rxjs/Observable": "Rx",
  "rxjs/Subject": "Rx",
  "rxjs/Subscription": "Rx",
  "rxjs/observable/fromPromise": "Rx.Observable",
  "rxjs/observable/forkJoin": "Rx.Observable",
  "rxjs/observable/fromEvent": "Rx.Observable",
  "rxjs/observable/merge": "Rx.Observable",
  "rxjs/observable/of": "Rx.Observable",
  "rxjs/operator/auditTime": "Rx.Observable.prototype",
  "rxjs/operator/catch": "Rx.Observable.prototype",
  "rxjs/operator/debounceTime": "Rx.Observable.prototype",
  "rxjs/operator/distinctUntilChanged": "Rx.Observable.prototype",
  "rxjs/operator/do": "Rx.Observable.prototype",
  "rxjs/operator/filter": "Rx.Observable.prototype",
  "rxjs/operator/finally": "Rx.Observable.prototype",
  "rxjs/operator/first": "Rx.Observable.prototype",
  "rxjs/operator/map": "Rx.Observable.prototype",
  "rxjs/operator/pluck": "Rx.Observable.prototype",
  "rxjs/operator/startWith": "Rx.Observable.prototype",
  "rxjs/operator/switchMap": "Rx.Observable.prototype",
  "rxjs/operator/takeUntil": "Rx.Observable.prototype",
  "rxjs/operator/throttleTime": "Rx.Observable.prototype",
};

if (format === "es") {
  globals = Object.assign(globals, {
    tslib: "tslib",
  });
}

let input;
let file;

switch (format) {
  case "es":
    input = "./publish/src/index.js";
    file = "./publish/esm15/index.js";
    break;
  case "umd":
    input = "./publish/esm5/index.js";
    file = "./publish/bundles/ng-kylin.umd.js";
    break;
  default:
    throw new Error(`format ${format} is not supported`);
}

export default {
  input,
  output: {
    file,
    format,
  },
  exports: "named",
  name: "ngKylin",
  plugins: [replace({ "import * as moment": "import moment" }), resolve()],
  external: Object.keys(globals),
  globals,
};

shell 腳本定義執行流程(build.sh)

#!/usr/bin/env bash

rm -rf ./publish

cp -r src/app/components src/temp_components

node ./html.merge.js

echo 'Generating entry file using Angular compiler'
$(npm bin)/ngc -p tsconfig-aot.json
rm -rf src/temp_components

echo 'Bundling to es module'
export ROLLUP_FORMAT=es
$(npm bin)/rollup -c rollup-config.js
rm -rf publish/src/*.js
rm -rf publish/src/**/*.js
sed -e "s/from '.\//from '.\/src\//g" publish/src/index.d.ts > publish/index.d.ts
sed -e "s/\":\".\//\":\".\/src\//g" publish/src/index.metadata.json > publish/index.metadata.json
rm publish/src/index.d.ts publish/src/index.metadata.json

echo 'Transpiling es module to es5'
$(npm bin)/tsc --allowJs --importHelpers --target es5 --module es2015 --outDir publish/esm5 publish/esm15/index.js

echo 'Bundling to umd module'
export ROLLUP_FORMAT=umd
$(npm bin)/rollup -c rollup-config.js

echo 'Minifying umd module'
$(npm bin)/uglifyjs publish/bundles/ng-kylin.umd.js --output publish/bundles/ng-kylin.umd.min.js

echo 'Copying package.json'
cp package.json publish/package.json

至此，項目打包結束。