自定义loader基础知识

// loaders/myLoader.js 返回的值是js模块代码，这个loader属于最左loader
module.exports = function loader(source) {
    return `module.exports = {fn: ${source}}`;
};

// main.js
const src = require("./src")
src.fn();

// src.js
alert(999)

//配置文件
const path = require(‘path‘)
module.exports = {
    entry:  [__dirname + "/main.js"],
    output: {
        path: __dirname + "/dist",
        filename: "bundle.js",
    },
    module: {
        loaders:[
            {
                test: /src.js/,
                use: [
                    {
                        loader: path.resolve(__dirname, ‘./loaders/myLoader.js‘),
                    }
                ]
            }
        ]
    }
}

/***/ }),
/* 1 */
/***/ (function(module, exports, __webpack_require__) {

const src = __webpack_require__(2)
src.fn();

/***/ }),
/* 2 */
/***/ (function(module, exports) {

module.exports = {fn: alert(999)}

/***/ })
/******/ ]);

module.exports = function(source) {
    var callback = this.async();
    setTimeout(function(){
       callback(null,`module.exports = {fn: ${source}}`)
    },5000);
};