Catching and handling Uglify errors when using Gulp

Question

My Gulp setup is otherwise working fantastically, but it stops if there's an error with my JS files. Until Gulp 4 is finally released, we're all stuck using the less than perfect error system in Gulp... So how can I catch Uglify's errors?

gulp.task('js', function() {
    return gulp
        .src(inputJS)
        .pipe(sourcemaps.init())
        .pipe(concat('main.js'))
        .pipe(uglify(uglifyOptions))
        .pipe(sourcemaps.write('./maps'))
        .pipe(gulp.dest(outputJS))
});

According to the Uglify documentation, gulp-uglify emits an 'error' event if it is unable to minify a specific file. Wherever possible, the PluginError object will contain the following properties: fileName, lineNumber, message.

The closest I've gotten it to working is: .on('error', function(uglify) { console.error(uglify.message) })), but it ends up with the above Gulp task ceasing to do any more.

Edit: I realise that there's a number of Gulp extensions that help when dealing with error handling (eg. Gulp-Util, Stream-Combiner2, Gulp-Plumber, etc.) but I don't wish to install a whole new extension just for Uglify (I'm handling my Sass errors just fine without one).

Why do you have an avatar from one of the worst Star Trek episodes?! — Martin Tournoij
– Martin Tournoij, Commented Nov 16, 2015 at 17:00

Chuck Le Butt · Accepted Answer · 2015-11-16 17:53:22Z

11

It seems the solution was very simple:

    .pipe(uglify(uglifyOptions).on('error', function(uglify) {
        console.error(uglify.message);
        this.emit('end');
    }))

Almost exactly what Jeffwa suggested, but no need for gulp-plumber. The reason my attempt was stopping is because Gulp watch tasks wait until they receive end (see: https://github.com/gulpjs/gulp/issues/259).

edited Nov 16, 2015 at 17:53

answered Nov 16, 2015 at 17:47

Chuck Le Butt

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1 Comment

Kareem Over a year ago

@Chunck It works but the reference for the error is filename: 'script.js' in the /dist folder. How do I find out which js file before concat'ing is the reason for the error? Thanks in advance.

Jeffwa · Accepted Answer · 2015-11-16 13:34:53Z

1

Maybe gulp-plumber will help.

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

gulp.task('js', function() {
    return gulp
        .src(inputJS)
        .pipe(plumber(function(error) {
            console.error(error.message);
            gulp.emit('finish');
        }))
        .pipe(sourcemaps.init())
        .pipe(concat('main.js'))
        .pipe(uglify(uglifyOptions))
        .pipe(sourcemaps.write('./maps'))
        .pipe(gulp.dest(outputJS))
});

That should catch any errors emitted and write them to the console.

answered Nov 16, 2015 at 13:34

Jeffwa

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