Breakpoints in Chrome not working with Sourcemap

Question

This is the most annoying problem. I've run into this before here, however I have the same setup in my webpack config and gulp and I cannot set breakpoints correctly in the Chrome Devtools.

I've deleted my app file and map, re-run gulp webpack which auto-generates it again, and it still does not break where I want too in the app :(

Webpack config

var webpack = require('webpack');
var PROD = JSON.parse(process.env.PROD_DEV || '0');
// https://stackoverflow.com/questions/25956937/how-to-build-minified-and-uncompressed-bundle-with-webpack

module.exports = {
    entry: "./entry.js",
    devtool: "source-map",
    output: {
        devtoolLineToLine: true,
        sourceMapFilename: "tickertags.bundle.js.map",
        pathinfo: true,
        path: __dirname,
        filename: PROD ? "tickertags.bundle.min.js" : "tickertags.bundle.js"
    },
    module: {
        loaders: [
            { test: /\.css$/, loader: "style!css" }
        ]
    },
    plugins: PROD ? [
        new webpack.optimize.UglifyJsPlugin({ minimize: true })
    ] : []
};

Gulp tasks

gulp.task('webpack',['build:html-templates'],function() {
    return gulp.src('entry.js')
    .pipe(webpack( require('./webpack.config.js') ))
    .pipe(gulp.dest('app/assets/js'));
});

// Development watch /////////////////////////////////////////////////////////// ☕️⏎→
gulp.task('watch', function() {
    gulp.watch('app/**/**/*.html', ['build:html-templates']).on('change', function(file) {
        var filePath = file.path.split(rootPath);
        process.stdout.write(gutil.colors.red(' →→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→   ' +filePath[1]+ '\n'));
    });

    gulp.watch('app/assets/imgs/*.svg').on('change', function(file) {
        var filePath = file.path.split(rootPath);
        process.stdout.write(gutil.colors.red(' →→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→   ' +filePath[1]+ '\n'));
    });

    gulp.watch('sass-smacss/sass/**/*.scss', ['app-css']).on('change', function(file) {
        var filePath = file.path.split(rootPath);
        process.stdout.write(gutil.colors.red(' →→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→   ' +filePath[1]+ '\n'));
    });

    gulp.watch(paths.scripts, ['webpack']).on('change', function(file) {
        var filePath = file.path.split(rootPath);
        process.stdout.write(gutil.colors.red(' →→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→   ' +filePath[1]+ '\n'));
    });
});

gulp.task('default', ['watch', 'webpack']);

Answer 1

Sourcemaps are broken on the current version of Chrome: https://bugs.chromium.org/p/chromium/issues/detail?id=611328#c21

Once source maps are fixed (the fix is currently in canary), then I'm sure breakpoints with sourcemaps will be fixed as well.

EDIT: Last link was an outdated bug, the one linked above is current.

Answer 2

To my knowledge the only solution is to not use sourcemaps with minified code. Either compile your code without minification, or use chrome dev tools's builtin pretty-print feature. The problem is that minification usually compresses multiple lines into a comma expression. Comma expressions are not interpreted as separate statements by the dev tools, thats why you only can put breakpoints on the beginning of code blocks. Sourcemaps just convert back the textual representation of the minified code, but the engine executes them by lines in the minified code.

EDIT

See if disabling sourcemaps helps, this is where you find the setting in Chrome:

Open the developer console, press F1, and find the following checkbox

Answer 3

FOUND THE PROBLEMATIC PIECE OF CODE

var alertVolumeUrl = function(ticker, term_id) {
    var url = api.alertsVolume;
    return _.isEmpty(term_id) ? url + ticker : url;
};

function alertsVolume(ticker, params) { 

    var url = alertVolumeUrl(ticker, params.term_id);
    return $http.get(url, {params: params}).then(function(res){
        return res.data.alerts;
});

---

I had to rewrite the 2nd function like so:

var alertVolumeUrl = function(ticker, term_id) {
    var url = '/app/api/alerts/volume/';
    return _.isEmpty(term_id) ? url + ticker : url;
};

var alertsVolume = function(ticker, params) {
    return $http.get(alertVolumeUrl(ticker, params.term_id), { params: params }).then(function(res){
        return res.data.alerts;
    });
};

Note how alertVolumeUrl is being used in the 2nd function now.

That for some reason was causing our breakpoints to fail.