I am trying to use gulp in order to minify a folder containing JS files. However, one of the files has the above error, preventing it from being minified.
I managed to catch and print the error, which I've partially printed here:
JS_Parse_Error {
message: 'SyntaxError: Unexpected token: punc ())',
filename: 'ex.js',
line: 189,
col: 25,
pos: 6482,
stack: Error\n at new JS_Parse_Error (eval at <anonymous> ... )
plugin: 'gulp-uglify',
fileName: '.../js/ex.js',
showStack: false
}
The file in question contains the following, shortened:
function() {
...
$.confirm({
buttons: {
confirm: function() {
$.post('/ajax-handler', {
...
})
.done( function(response) {
var data = filterResponse(response);
if (data['status'] == 'success') {
sleep(1000).then(() => {
* ...
});
sleep(5000).then(() => {
...
});
} else {
console.log('Oops!');
}
})
.fail( function(err, status, response) {
...
});
},
cancel: function() {}
}
});
...
}
I added the "*" above in order to indicate the exact position listed by JS_Parse_Error.
v2.0.0 (2018-09-14) - BREAKING CHANGES (link)
Switch back to uglify-js (uglify-es is abandoned, if you need uglify ES6 code please use terser-webpack-plugin).
I hope you can get inspired by this solution which works with webpack. (link below)
There are two versions of UglifyJS - ES5 and ES6 (Harmony), see on git
ES5 version comes by default with all the plugins, but if you install a Harmony version explicitly, those plugins will use it instead.
package.json
"uglify-js": "git+https://github.com/mishoo/UglifyJS2.git#harmony"
or
npm install --save uglify-js@github:mishoo/UglifyJS2#harmony
yarn add git://github.com/mishoo/UglifyJS2#harmony --dev
To use it with webpack install also the webpack plugin
npm install uglifyjs-webpack-plugin --save-dev
yarn add uglifyjs-webpack-plugin --dev
then import the manually installed plugin
var UglifyJSPlugin = require('uglifyjs-webpack-plugin');
and replace it in code
- new webpack.optimize.UglifyJsPlugin({ ... })
+ new UglifyJSPlugin({ ... })
For more webpack info (Installation/Usage) see https://github.com/webpack-contrib/uglifyjs-webpack-plugin#install
npm install uglifyjs-webpack-plugin --save-dev is not enough
The main problem is "uglifyjs-webpack-plugin": "^0.4.6" in webpack's package.json
According to semver, ^0.4.6 := >=0.4.6 <0.5.0. Because of the leading zero, webpack will never use the 1.0.0-beta.2.
So after running npm i -D uglifyjs-webpack-plugin@beta, you need to do one more step which is rm -rf node_modules/webpack/node_modules/uglifyjs-webpack-plugin. Then webpack will pick up the version from node_modules/uglifyjs-webpack-plugin instead of node_modules/webpack/node_modules/uglifyjs-webpack-plugin
Update on 2018-04-18: webpack v4 does not have this issue
Add the babel-preset-es2015 dependency to fix this.
And also add 'es2015' in .babelrc file.
json
{
"presets": ["es2015"]
}