gulp-if

What is gulp-if?

The gulp-if package is a conditional plugin for Gulp that allows you to conditionally control the flow of your Gulp tasks. It is particularly useful for running tasks only if certain conditions are met, such as environment variables, file types, or custom logic.

What are gulp-if's main functionalities?

Conditional Task Execution

This feature allows you to conditionally execute tasks based on a condition. In this example, the 'uglify' task is only run if the environment is set to 'production'.

const gulp = require('gulp');
const gulpIf = require('gulp-if');
const uglify = require('gulp-uglify');

const isProduction = process.env.NODE_ENV === 'production';

gulp.task('scripts', function() {
  return gulp.src('src/js/*.js')
    .pipe(gulpIf(isProduction, uglify()))
    .pipe(gulp.dest('dist/js'));
});

Conditional File Handling

This feature allows you to conditionally handle files based on their properties. In this example, the 'cssnano' task is only run on files with a '.css' extension.

const gulp = require('gulp');
const gulpIf = require('gulp-if');
const cssnano = require('gulp-cssnano');
const isCSS = (file) => file.extname === '.css';

gulp.task('styles', function() {
  return gulp.src('src/styles/*')
    .pipe(gulpIf(isCSS, cssnano()))
    .pipe(gulp.dest('dist/styles'));
});

Custom Condition Functions

This feature allows you to use custom functions to determine whether a task should be executed. In this example, files larger than 1MB are renamed with a '-large' suffix.

const gulp = require('gulp');
const gulpIf = require('gulp-if');
const rename = require('gulp-rename');

const isLargeFile = (file) => file.stat.size > 1024 * 1024; // 1MB

gulp.task('rename-large-files', function() {
  return gulp.src('src/files/*')
    .pipe(gulpIf(isLargeFile, rename({ suffix: '-large' })))
    .pipe(gulp.dest('dist/files'));
});

Other packages similar to gulp-if

gulp-filter

The gulp-filter package allows you to filter files in a stream based on a condition, similar to gulp-if. However, gulp-filter is more focused on filtering files out of a stream rather than conditionally applying tasks.

through2

The through2 package is a general-purpose stream utility that can be used to create custom conditional logic in Gulp tasks. While not as specialized as gulp-if, it offers greater flexibility for advanced use cases.

README

gulp-if

A ternary gulp plugin: conditionally control the flow of vinyl objects.

Note: Badly behaved plugins can often get worse when used with gulp-if. Typically the fix is not in gulp-if.

Note: Works great with lazypipe, see below

Usage

1: Conditionally filter content

Condition

var gulpif = require('gulp-if');
var uglify = require('gulp-uglify');

var condition = true; // TODO: add business logic

gulp.task('task', function() {
  gulp.src('./src/*.js')
    .pipe(gulpif(condition, uglify()))
    .pipe(gulp.dest('./dist/'));
});

Only uglify the content if the condition is true, but send all the files to the dist folder

2: Ternary filter

Ternary

var gulpif = require('gulp-if');
var uglify = require('gulp-uglify');
var beautify = require('gulp-beautify');

var condition = function (file) {
  // TODO: add business logic
  return true;
}

gulp.task('task', function() {
  gulp.src('./src/*.js')
    .pipe(gulpif(condition, uglify(), beautify()))
    .pipe(gulp.dest('./dist/'));
});

If condition returns true, uglify else beautify, then send everything to the dist folder

3: Remove things from the stream

Remove from here on

var gulpIgnore = require('gulp-ignore');
var uglify = require('gulp-uglify');
var jshint = require('gulp-jshint');

var condition = './gulpfile.js';

gulp.task('task', function() {
  gulp.src('./*.js')
    .pipe(jshint())
    .pipe(gulpIgnore.exclude(condition))
    .pipe(uglify())
    .pipe(gulp.dest('./dist/'));
});

Run JSHint on everything, remove gulpfile from the stream, then uglify and write everything else.

4: Exclude things from the stream

Exclude things from entering the stream

var uglify = require('gulp-uglify');

gulp.task('task', function() {
  gulp.src(['./*.js', '!./node_modules/**'])
    .pipe(uglify())
    .pipe(gulp.dest('./dist/'));
});

Grab all JavaScript files that aren't in the node_modules folder, uglify them, and write them. This is fastest because nothing in node_modules ever leaves gulp.src()

works great with lazypipe

Lazypipe creates a function that initializes the pipe chain on use. This allows you to create a chain of events inside the gulp-if condition. This scenario will run jshint analysis and reporter only if the linting flag is true.

var gulpif = require('gulp-if');
var jshint = require('gulp-jshint');
var uglify = require('gulp-uglify');
var lazypipe = require('lazypipe');

var linting = false;
var compressing = false;

var jshintChannel = lazypipe()
  // adding a pipeline step
  .pipe(jshint) // notice the stream function has not been called!
  .pipe(jshint.reporter)
  // adding a step with an argument
  .pipe(jshint.reporter, 'fail');

gulp.task('scripts', function () {
  return gulp.src(paths.scripts.src)
    .pipe(gulpif(linting, jshintChannel()))
    .pipe(gulpif(compressing, uglify()))
    .pipe(gulp.dest(paths.scripts.dest));
});

source

works great inside lazypipe

Lazypipe assumes that all function parameters are static, gulp-if arguments need to be instantiated inside each lazypipe. This difference can be easily solved by passing a function on the lazypipe step

var gulpif = require('gulp-if');
var jshint = require('gulp-jshint');
var uglify = require('gulp-uglify');
var lazypipe = require('lazypipe');

var compressing = false;

var jsChannel = lazypipe()
  // adding a pipeline step
  .pipe(jshint) // notice the stream function has not been called!
  .pipe(jshint.reporter)
  // adding a step with an argument
  .pipe(jshint.reporter, 'fail')
  // you can't say: .pipe(gulpif, compressing, uglify)
  // because uglify needs to be instantiated separately in each lazypipe instance
  // you can say this instead:
  .pipe(function () {
    return gulpif(compressing, uglify());
  });
  // why does this work? lazypipe calls the function, passing in the no arguments to it,
  // it instantiates a new gulp-if pipe and returns it to lazypipe.

gulp.task('scripts', function () {
  return gulp.src(paths.scripts.src)
    .pipe(jsChannel())
    .pipe(gulp.dest(paths.scripts.dest));
});

source

gulp-if API

gulpif(condition, stream [, elseStream, [, minimatchOptions]])

gulp-if will pipe data to stream whenever condition is truthy.

If condition is falsey and elseStream is passed, data will pipe to elseStream

After data is piped to stream or elseStream or neither, data is piped down-stream.

Parameters

condition

Type: boolean or stat object or function that takes in a vinyl file and returns a boolean or RegularExpression that works on the file.path

The condition parameter is any of the conditions supported by gulp-match. The file.path is passed into gulp-match.

If a function is given, then the function is passed a vinyl file. The function should return a boolean.

stream

Stream for gulp-if to pipe data into when condition is truthy.

elseStream

Optional, Stream for gulp-if to pipe data into when condition is falsey.

minimatchOptions

Optional, if it's a glob condition, these options are passed to minimatch.

LICENSE

(MIT License)

Copyright (c) 2014 Richardson & Sons, LLC

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.