TypeError [ERR_INVALID_CALLBACK]:回调必须是函数

Question

我想创建一个脚本来向angular webpack app添加一个新规则,如下所示.有时代码执行部分,有时它会给出erorr.

const fs = require('fs');
const commonCliConfig = 'node_modules/@angular-devkit/build-angular/src/angular-cli-files/models/webpack-configs/common.js';
const pug_rule = "\n{ test: /\\.pug$/, loader: ['raw-loader' , 'pug-html-loader' ]},";
var configText = "";
fs.readFile(commonCliConfig, function(err, data) {
    if (err) throw err;
    configText = data.toString();
    if (configText.indexOf(pug_rule) > -1) { return; }
    const position = configText.indexOf('rules: [') + 8;
    const output = [configText.slice(0, position), pug_rule, configText.slice(position)].join('');
    const file = fs.openSync(commonCliConfig, 'r+');
    fs.writeFile(file, output);
    fs.close(file);
});


Terminal node pug-rule.js
fs.js:148
    throw new ERR_INVALID_CALLBACK();
    ^

TypeError [ERR_INVALID_CALLBACK]: Callback must be a function
    at makeCallback (fs.js:148:11)
    at Object.fs.close (fs.js:520:20)
    at path/pug-rule.js:18:5
    at FSReqWrap.readFileAfterClose [as oncomplete] (fs.js:422:3)

Answer 1

fs.writeFile(...)需要第三个(或第四个)参数,这是一个在操作完成时调用的回调函数.您应该提供回调函数或使用fs.writeFileSync(...)

有关详细信息,请参阅node fs docs.