gulp 流处理

包含的内容：

    穿插流

    流合并

    流队列

    流筛选

1. 穿插流

// passthrough  stream  把流传递给其他的

// use

gulp.src(glob,{passthrough:true})

// function
进行流的合并处理，避免多余配置以及冗余代码

2. 合并流

// 使用merge2

// install 

yarn  add merge2  or  npm install merge2

// use

const gulp = require('gulp')
const merge2 = require('merge2')
const concat = require('gulp-concat')
const minifyHtml = require('gulp-minify-html')
const ngtemplate = require('gulp-ngtemplate')

gulp.task('app-js', function () {
  return merge2(
      gulp.src('static/src/tpl/*.html')
        .pipe(minifyHtml({empty: true}))
        .pipe(ngtemplate({
          module: 'genTemplates',
          standalone: true
        })
      ), gulp.src([
        'static/src/js/app.js',
        'static/src/js/locale_zh-cn.js',
        'static/src/js/router.js',
        'static/src/js/tools.js',
        'static/src/js/services.js',
        'static/src/js/filters.js',
        'static/src/js/directives.js',
        'static/src/js/controllers.js'
      ])
    )
    .pipe(concat('app.js'))
    .pipe(gulp.dest('static/dist/js/'))
})

3. 流队列

// 使用 streamqueue
//use

var StreamQueue = require('streamqueue');
var queue = new StreamQueue();
queue.queue(
 gulp.src('static/src/tpl/*.html')
        .pipe(minifyHtml({empty: true}))
        .pipe(ngtemplate({
          module: 'genTemplates',
          standalone: true
        })
      ), gulp.src([
        'static/src/js/app.js',
        'static/src/js/locale_zh-cn.js',
        'static/src/js/router.js',
        'static/src/js/tools.js',
        'static/src/js/services.js',
        'static/src/js/filters.js',
        'static/src/js/directives.js',
        'static/src/js/controllers.js'
      ])
);
queue.pipe(process.stdout);

4. 流修改

// 使用 gulp-filter

// use

const gulp = require('gulp');
const uglify = require('gulp-uglify');
const filter = require('gulp-filter');

gulp.task('default', () => {
    // Create filter instance inside task function
    const f = filter(['**', '!*src/vendor']);

    return gulp.src('src/**/*.js')
        // Filter a subset of the files
        .pipe(f)
        // Run them through a plugin
        .pipe(uglify())
        .pipe(gulp.dest('dist'));
});

参考文档
https://www.npmjs.com/package/gulp-filter

5. 顺序流、并行流

// gulp-series  gulp.parallel (4.0)
// use

gulp.series
gulp.task("scripts",gulp.series("test","deploy"))

gulp.parallel
gulp.tast("mixs",gulp.series("clean",gulp.parallel("style","scripts")))