每次在命令行中运行 gulp 时出现断言错误

本文介绍了每次在命令行中运行 gulp 时出现断言错误的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着跟版网的小编来一起学习吧！

问题描述

我正在尝试运行下面的命令，但不幸的是我遇到了错误.

I'm trying to run the command below but unfortunately I run into an error.

C:UsersusverDesktopgit testgitBootstrap4conFusion>gulp

运行上述命令后出现断言错误.我再次重新安装了 gulp 和 npm，但得到了同样的错误.我的节点版本-v10.15.0吞咽版本-CLI 版本 2.0.1本地版本 4.0.2

I got assertion error after running the above command. I reinstalled gulp and npm once again but got the same error. My node version-v10.15.0 gulp version- CLI version 2.0.1 Local version 4.0.2

assert.js:350
    throw err;
    ^

AssertionError [ERR_ASSERTION]: Task function must be specified
    at Gulp.set [as _setTask] (C:UsersusverDesktopgit testgitBootstrap4conFusion
ode_modulesundertakerlibset-task.js:10:3)
    at Gulp.task (C:UsersusverDesktopgit testgitBootstrap4conFusion
ode_modulesundertakerlib	ask.js:13:8)
    at Object.<anonymous> (C:UsersusverDesktopgit testgitBootstrap4conFusiongulpfile.js:30:6)
    at Module._compile (internal/modules/cjs/loader.js:689:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:700:10)
    at Module.load (internal/modules/cjs/loader.js:599:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:538:12)
    at Function.Module._load (internal/modules/cjs/loader.js:530:3)
    at Module.require (internal/modules/cjs/loader.js:637:17)
    at require (internal/modules/cjs/helpers.js:22:18)

我使用 Windows 10 操作系统和 VS Code 作为编辑器.

I m Using Windows 10 Operating System and VS Code as an editor.

gulp.js 文件:

gulp.js file:

'use strict';

var gulp=require('gulp'),
    sass=require('gulp-sass'),
    browserSync=require('browser-sync');
gulp.task('sass',function(){
    return gulp.src('./css/*.scss')
    .pipe(sass().on('error',sass.logerror))
    .pipe(gulp.dest('./css'));
});

gulp.task('sass:watch',function(){
    gulp.watch('./css/*.scss',['sass']);
});
gulp.task('browser-sync',function(){
    var files=[
        './*.html',
        './css/*.css',
        './js/*.js',
        './img/*.{png,jpg,gif}'
    ];

    browserSync.init(files,{
        server:{
            baseDir:'./'
        }
    });
});


gulp.task('default',['browser-sync'],function(){
    gulp.start('sass:watch');
});`

package.json 文件

package.json file

{
  "name": "confusion",
  "version": "1.0.0",
  "description": "This is a website for Ristorante Con Fusion",
  "main": "index.html",
  "scripts": {
    "start": "npm run watch:all",
    "test": "echo "Error: no test specified" && exit 1",
    "lite": "lite-server",
    "scss": "node-sass -o css/ css/",
    "watch:scss": "onchange "css/*.scss" --npm run scss",
    "watch:all": "parallelshell "npm run watch:scss" 'npm run lite'",
    "clean": "rimraf dist",
    "copyfonts": "copyfiles -f node_modules/font-awesome/fonts/* dist/fonts",
    "imagemin": "imagemin img/* -o dist/img",
    "usemin": "usemin contactus.html -d dist --htmlmin -o dist/contactus.html && usemin aboutus.html -d dist --htmlmin -o dist/aboutus.html && usemin index.html -d dist --htmlmin -o dist/index.html",
    "build": "npm run clean && npm run copyfonts && npm run imagemin && npm run usemin"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "browser-sync": "^2.26.7",
    "cssmin": "^0.4.3",
    "del": "^3.0.0",
    "grunt-browser-sync": "^2.2.0",
    "grunt-cli": "^1.2.0",
    "grunt-contrib-clean": "^1.1.0",
    "grunt-contrib-concat": "^1.0.1",
    "grunt-contrib-copy": "^1.0.0",
    "grunt-contrib-cssmin": "^2.2.1",
    "grunt-contrib-htmlmin": "^2.4.0",
    "grunt-contrib-imagemin": "^3.1.0",
    "grunt-contrib-uglify": "^3.3.0",
    "grunt-contrib-watch": "^1.1.0",
    "grunt-filerev": "^2.3.1",
    "grunt-sass": "^2.1.0",
    "grunt-usemin": "^3.1.1",
    "gulp": "^4.0.2",
    "gulp-sass": "^3.1.0",
    "htmlmin": "0.0.7",
    "jit-grunt": "^0.10.0",
    "lite-server": "^2.3.0",
    "node-sass": "^4.12.0",
    "onchange": "^6.0.0",
    "parallelshell": "^3.0.2",
    "rimraf": "^2.6.2",
    "time-grunt": "^1.4.0",
    "uglifyjs": "^2.4.11",
    "usemin-cli": "^0.5.1"
  },
  "dependencies": {
    "bootstrap": "^4.3.1",
    "bootstrap-social": "^5.1.1",
    "font-awesome": "^4.7.0",
    "grunt": "^1.0.4",
    "jquery": "^3.4.1",
    "popper.js": "^1.12.9"
  }
}

我已经包含 gulp.js 和 package.json 文件.

I've include gulp.js and package.json file.

推荐答案

您在 gulp4 文件中使用 gulp3 语法.

You are using gulp3 syntax in a gulp4 file.

搜索你的错误信息Task function must be specified，你会得到很多点击.

Search your error message Task function must be specified and you will get lots of hits.

更改这些行:

gulp.task('sass:watch',function(){
    // gulp.watch('./css/*.scss',['sass']);

    gulp.watch('./css/*.scss', gulp.series('sass'));
    // gulp.watch('./css/*.scss', 'sass');    // should work too
});

和

// gulp.task('default',['browser-sync'],function(){
    //gulp.start('sass:watch');
// });

到

gulp.task('default', gulp.series('browser-sync', 'sass:watch'));

看起来您正在学习旧的 gulp3 教程，但请寻找一些从 gulp3 到 gulp4 的迁移指南.

It looks like you were working off of an old gulp3 tutorial but look for some migration guides from gulp3 to gulp4 instead.

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每次在命令行中运行 gulp 时出现断言错误

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