gulp: passing dependent task return stream as parameter

问题

I'm trying to create two gulp tasks, and I'd like the second task to take the first one's output stream and keep applying plugins to it.

Can I pass the first task's return value to the second task?

The following doesn't work:

// first task to be run
gulp.task('concat', function() {
  // returning a value to signal this is sync
  return
    gulp.src(['./src/js/*.js'])
      .pipe(concat('app.js'))
      .pipe(gulp.dest('./src'));
};

// second task to be run
// adding dependency
gulp.task('minify', ['concat'], function(stream) {
  // trying to get first task's return stream
  // and continue applying more plugins on it
  stream
    .pipe(uglify())
    .pipe(rename({suffix: '.min'}))
    .pipe(gulp.dest('./dest'));
};

gulp.task('default', ['minify']);

Is there any way to do this?

回答1:

you can't pass stream to other task. but you can use gulp-if module to skip some piped method depending on conditions.

var shouldMinify = (0 <= process.argv.indexOf('--uglify'));

gulp.task('script', function() {
  return gulp.src(['./src/js/*.js'])
      .pipe(concat('app.js'))
      .pipe(gulpif(shouldMinify, uglify())
      .pipe(gulpif(shouldMinify, rename({suffix: '.min'}))
      .pipe(gulp.dest('./dest'));
});

execute task like this to minify

gulp script --minify

回答2:

I am looking for the same solution, but ended up just chaining functions. This is quite flexible. Please share if anyone has better solution without using additional packages.

function concatenate() {
      return gulp
            .src(['./src/js/*.js'])
            .pipe(concat('app.js'));
}

function minify() {
      return this
            .pipe(uglify())
            .pipe(rename({suffix: '.min'}));
}

function output() {
      return this.pipe(gulp.dest('./src'));
}

gulp.task('concat', function() {
      return output.call(concatenate());
});

gulp.task('minify', function() {
      return output.call(minify.call(concatenate()));
});

gulp.task('default', ['minify']);

来源：https://stackoverflow.com/questions/30361051/gulp-passing-dependent-task-return-stream-as-parameter

标签

gulp