英文:
Rails Gem Uglifier 4.2 does not support async/await, how to fix
问题
I have a Ruby on Rails project which uses some Javascript in the frontend. In development mode this runs fine, but when trying to build a Docker container (which compiles the assets) Uglifier gives an error Uglifier::Error: Unexpected token: operator (=). The offending code is:
var MyController = (function() {
let self = undefined;
MyController = class MyController {
constructor() {
self = this;
}
init() {...}
... // lots more code
loadAsync = async (targetElement, num) => { // <= this is the offending line
await this.delay(5);
$.ajax({
url: `...`,
method: 'GET',
dataType: 'HTML',
complete(response) {
...
}
});
};
delay = ms => new Promise(res => setTimeout(res, ms));
...
英文:
I have a Ruby on Rails project which uses some Javascript in the frontend. In development mode this runs fine, but when trying to build a Docker container (which compiles the assets) Uglifier gives an error Uglifier::Error: Unexpected token: operator (=). The offending code is:
var MyController = (function() {
let self = undefined;
MyController = class MyController {
constructor() {
self = this;
}
init() {...}
... // lots more code
loadAsync = async (targetElement, num) => { // <= this is the offending line
await this.delay(5);
$.ajax({
url: `...`,
method: 'GET',
dataType: 'HTML',
complete(response) {
...
}
});
};
delay = ms => new Promise(res => setTimeout(res, ms));
...
I know that Uglifier uses UglifyJS under the hood, and that this used to have problems with async/await. Are there versions available now that have this problem fixed, and if so, how do I install a working version? I use the newest Uglifier gem version available (4.2), using the options harmony: true, mangle: false.
答案1
得分: 2
Uglifier readme 中写道：
> UglifyJS 仅支持 ES5。如果需要压缩 ES6，ruby-terser 是一个更好的选择。
切换到 ruby-terser 是一种选择。您还可以使用 Babel 将 ES6 转译为 ES5。
英文:
The Uglifier readme says
> UglifyJS only works with ES5. If you need to compress ES6, ruby-terser
> is a better option.
Switching to ruby-terser is an option. You could also use Babel to transpile ES6 into ES5.
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