Cherry-pick terser to webpack 4 #8392
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Some history: * `uglifyjs-webpack-plugin` < v1.0 used the minifier `uglify-js` * however `uglify-js` does not support ES6, which resulted in a fork called `uglify-es` that was developed in the `uglify-js` repository, but under the `harmony` branch * `uglifyjs-webpack-plugin` v1.x switched to `uglify-es` for ES6 support * however `uglify-es` stopped being maintained: mishoo/UglifyJS#3156 (comment) * which led to a fork called `terser` that has incorporated all of the unmerged PRs and will be where all new development occurs: https://github.com/fabiosantoscode/terser * `terser-webpack-plugin` was created, which is the `terser` equivalent of `uglifyjs-webpack-plugin`: https://github.com/webpack-contrib/terser-webpack-plugin * `uglifyjs-webpack-plugin` v2.x will be switching back to `uglify-js`, so any project that needs to support ES6 now needs to switch to `terser-webpack-plugin`. Fixes #7923.
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For maintainers only:
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vkrol
changed the title
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Thank you for your pull request! The most important CI builds succeeded, we’ll review the pull request soon. |
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Be aware that |
We do not allow to pass these options when using the defaults. So that should not be a problem. To pass these options you have to override the defaults and include the terser/uglify plugin manually. The different warning messages may be a small breaking change for some users, but we have to accept this... |
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Thanks |
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Let's hope this doesn't break too much... Ready for some terser bug reports @kzc? This brings a lot of new users to terser... |
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I've created an issue to document this in webpack/webpack.js.org. |
Replaces the minifier we're using on prod builds from `uglify-js` to `terser`. Terser is a more updated replacement for UglifyJS. Webpack 4 switched to using it as the default minifier in Nov 2018 (webpack/webpack#8392). The reasons we'd want to switch: * Unblocks future updates to typescript output target; uglify only supports up to ES5 javascript, Terser supports more recent javascript as input * Closer to the "normal" webpack happy path * As of recently, [more widely used (with webpack)](https://www.npmtrends.com/uglifyjs-webpack-plugin-vs-terser-webpack-plugin) It is essentially a drop in replacement; we expect no customer-visible changes as a result of this update.
This PR #8036 was cherry-picked.
Motivation: #8350 (comment)
Issue: #8350
What kind of change does this PR introduce?
Bugfix.
Did you add tests for your changes?
N/A.
Does this PR introduce a breaking change?
No.
What needs to be documented once your changes are merged?
Default for the
optimization.minimizersoption need to be changed to TerserWebpackPlugin.