Uglify throws Parse error

Question

When i use gulp-uglify with browserify i get a error

events.js:72
        throw er; // Unhandled 'error' event
              ^
Error
    at new JS_Parse_Error (/home/rkmax/my-project/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:189:18)
    at js_error (/home/rkmax/my-project/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:197:11)
    at croak (/home/rkmax/my-project/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:656:9)
    at token_error (/home/rkmax/my-project/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:664:9)
    at expect_token (/home/rkmax/my-project/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:677:9)
    at expect (/home/rkmax/my-project/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:680:36)
    at /home/rkmax/my-project/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:1222:13
    at /home/rkmax/my-project/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:703:24
    at expr_atom (/home/rkmax/my-project/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:1152:35)
    at maybe_unary (/home/rkmax/my-project/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:1327:19)
    at expr_ops (/home/rkmax/my-project/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:1362:24)
    at maybe_conditional (/home/rkmax/my-project/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:1367:20)
    at maybe_assign (/home/rkmax/my-project/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:1391:20)
    at expression (/home/rkmax/my-project/node_modules/gulp-uglify/node_modules/uglify-js/lib/parse.js:1410:20)

this is my scripts task

gulp.task('scripts', function() {

    var bundler = browserify({
        entries: ['./src/scripts/main.js'],
        debug: debug
    }).transform(stringify()); // the error persist even without this transformation

    bundler
        .bundle()
        .on('error', handleErrors)
        .pipe(source(getBundleName() + '.js'))
        .pipe(jshint())
        .pipe(jshint.reporter('default', { verbose: true }))
        .pipe(jshint.reporter('fail'))
        .pipe(buffer())
        .pipe(sourcemaps.init({loadMaps: true}))
        .pipe(uglify())
        .pipe(sourcemaps.write('./'))
        .pipe(gulp.dest('./web/js'));
});

Answer 1

I encountered this same issue with gulp-concat-sourcemap and gulp-uglify. I solved it by ignoring map files with gulp-ignore:

gulp.task("uglify-src", function() {
    gulp.src([ "src/js/**/*.js" ])
    .pipe(concat("app.js"))
    .pipe(ignore.exclude([ "**/*.map" ]))
    .pipe(uglify())
    .pipe(gulp.dest("dist/js"));
});

Answer 2

It could be a simple error in your source JavaScript file. Try disabling uglify by commenting it out in your gulpfile and see if your browser console spots the real issue.

gulp.task('minified', function () {
    return gulp.src(paths.concatScripts)
        .pipe(sourcemaps.init())       
        //.pipe(uglify())
        .pipe(sourcemaps.write('.', { addComment: false }))        
        .pipe(gulp.dest(publishUrl));
}); 

Answer 3

Errors are not propagated by Node.js pipe. This article mentions @Marcos Abreu's uglify().on approach in addition to describing the use of pump instead of pipe.

https://github.com/terinjokes/gulp-uglify/blob/master/docs/why-use-pump/README.md#why-use-pump

Answer 4

uglify will parse the script content before minifying it. I suspect that one of the browserify source maps are being included in the stream down to uglify. Anyway to find the problem you can use gulp-util's log method to handle uglify's exceptions. Example:

...
var gulpUtil = require('gulp-util');

gulp.task('scripts', function() {
    ...
        .pipe(sourcemaps.init({loadMaps: true}))
        .pipe(uglify().on('error', gulpUtil.log)) // notice the error event here
        .pipe(sourcemaps.write('./'))
        .pipe(gulp.dest('./web/js'));
});

If you still have problems fixing the issue, post the details after incorporating the error log.