Conditionally run a task
npm install gulp-ifgulp-if !status
=======
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
javascript
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
![][ternary]
`javascript
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
![][exclude]
`javascript
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
![][glob]
`javascript
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.
`js
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
`js
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
$3
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`.