gulp-stream-to-promise

Convert gulp stream to promise.

Introduction

In Gulp 4, all task functions need be async, that means a task function needs to return a gulp stream, or a promise, etc.

With this feature, we can define multiple gulp streams as one gulp task. To do that, firstly we convert each gulp steam to promise, then combine them via Promise.all() to get one promise, finally return this all-in-one promise in the task function.

This package is to convert gulp streams to promises.

Usage

1. Install:

   $ npm install --save gulp-stream-to-promise

2. Require:

   const gulpStreamToPromise = require('gulp-stream-to-promise')

3. Convert:

   // we have a gulp stream here:
   let stream = gulp.src('path/to/src')
       .pipe(/* ... */)
       .pipe(gulp.dest('path/to/dest'))
    
   // convert it to a promise:
   let promise = gulpStreamToPromise(stream)

Example

const gulp = require('gulp')	// gulp 4
const concat = require('gulp-concat')
const gulpStreamToPromise = require('gulp-stream-to-promise')
 
// suppose we need to combine files according to this config:
const rules = {
    'foo.js': [
        './node_modules/foo/src/a.js',
        './node_modules/foo/src/b.js',
    ],
    'bar.js': [
        './src/c.js',
        './src/d.js',
    ],
}
 
gulp.task('js', () => {
    // array to contain each single combining operation:
    var tasks = []
 
    Object.keys(rules).forEach((filename) => {
        let src = rules[filename]
        
        // get a gulp stream for a combining operation:
        let stream = gulp.src(src)
            .pipe(concat(filename))
            .pipe(gulp.dest('path/to/dest'))
 
        // convert this gulp stream to a promise:
        let promise = gulpStreamToPromise(stream)
 
        // put into the array:
        tasks.push(promise)
    })
    
    // return the combined promise to complete the task function:
    return Promise.all(tasks)
})

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License

MIT License