gulp-function/docs/index.md

Usage

import * as gulp from 'gulp';
import gulpFunction from 'gulp-function' // default ES6 export
// import {forFirst, forEach, atEnd} from 'gulp-function'
let Q = require("q");

let myFunction = function (file, enc) { // file and enc are optional in case you want to modify the file object
    let done = Q.defer();
    console.log("Hello World!")
    
    // NOTE:
    // you can use done.resolve as callback function
    // of any async tasks within this function
    done.resolve();
    
    return done.promise;
}

gulp.task('gulpTest',function() {
    let stream = gulp.src('./mydir/*.something')
        .pipe(gulpFunction(myFunction,'forEach')) //read the notes below
        // .pipe(forEach(myFunction)) // if imported as >> import { forEach } from 'gulp-function' <<
        .pipe(gulp.dest("./build/"));
    return stream; // by returning the stream gulp knows when our task has finished.
});

Notes:

• The first argument of gulpFunction can also be an array of multiple functionnames. Each function can return a promise. The pipe stop will finish when every promise is fullfilled. When providing an array of functions be careful with modifying the file object -> race condition
• The second argument can be empty, it defaults to "forEach"
• The following options are available:
  • "forFirst" - executes when first chunk/vinylfile of the stream reaches the pipestop. file is pushed further down the line when function's returned promise is fullfilled.
  • "forEach" - executes like "forFirst" but with every chunk/vinylfile in the stream;
  • "atEnd" - executes after all chunks have passed and are processed in full. That means the stream's "finish" event fires before "atLast" is executed!!!