rollup.JS和"'this'关键字相当于'undefined'

Question

我正在尝试使用Rollup.js捆绑Angular2模块.这是我的rollup.config.vendor.js文件:

import typescript from 'rollup-plugin-typescript2';
import resolve from 'rollup-plugin-node-resolve';
import commonjs from 'rollup-plugin-commonjs';

export default {
    entry: 'vendor.ts',
    dest: './Bundle/vendor.js',
    format: 'iife',
    moduleName: 'vendor',
    plugins: [
        typescript(),
        resolve({
            jsnext: true,
            main: true,
            browser: true
        }),
        commonjs({
            include: 'node_modules/rxjs/**',
        }),
    ]
}

它创建了一个捆绑的js,但在这个过程中它会不断打印这种消息:

The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
https://github.com/rollup/rollup/wiki/Troubleshooting#this-is-undefined
node_modules\@angular\forms\@angular\forms.es5.js (1:25)
1: var __extends = (this && this.__extends) || function (d, b) {
                            ^
2:     for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
3:     function __() { this.constructor = d; }

这是什么意思？
我做错了什么,或者它应该是这样的？

Answer 1

您可以安全地忽略这些警告,如documentation通过将onwarn属性添加到您的rollup-config.js文件中所述:

onwarn: function(warning) {
    // Skip certain warnings

    // should intercept ... but doesn't in some rollup versions
    if ( warning.code === 'THIS_IS_UNDEFINED' ) { return; }

    // console.warn everything else
    console.warn( warning.message );
}

引用:

它会覆盖默认的onwarn方法,以便跳过有关AOT编译器使用this关键字的恼人消息.

Answer 2

您可以使用该context选项并将其设置为this：它避免重写thisto undefined（实际上this被重写为... this）。

请参阅汇总文档：

• https://rollupjs.org/guide/en/#error-this-is-undefined
• https://rollupjs.org/guide/en/#context