Non-dead JavaScript is removed during build
Created by: salomvary
Describe the bug
react-scripts build seems to be removing inline JavaScript code from index.html that should not be removed. It happens to code paths that are conditional and the condition contains a build-time '%VARIABLE%'.
Workaround: move the build-time variable outside of the condition.
Did you try recovering your dependencies?
No, it's a newly created project.
Which terms did you search for in User Guide?
NODE_ENV, index.html, variables
Environment
System:
OS: macOS 10.14.5
CPU: (4) x64 Intel(R) Core(TM) i5-5287U CPU @ 2.90GHz
Binaries:
Node: 8.16.0 - /usr/local/bin/node
Yarn: 1.17.3 - /usr/local/bin/yarn
npm: 6.10.1-salomvary1 - /usr/local/bin/npm
Browsers:
Chrome: 75.0.3770.142
Firefox: 68.0.1
Safari: 12.1.1
npmPackages:
react: ^16.8.6 => 16.8.6
react-dom: ^16.8.6 => 16.8.6
react-scripts: 3.0.1 => 3.0.1
npmGlobalPackages:
create-react-app: 3.0.1Steps to reproduce
- Create a new app with
create-react-app. - Edit
public/index.htmland add a the snipped below after<body>. - Run
npm run build. - Open
build/index.html
<script>
console.log('%NODE_ENV%');
var nodeEnv = '%NODE_ENV%';
if ('%NODE_ENV%' === 'production') {
console.log('This is production!');
}
if (nodeEnv === 'production') {
console.log('This is REALLY production!');
}
</script>Expected behavior
build/index.html should contain the minified version of the entire snippet with %NODE_ENV% replaced with production.
Actual behavior
This is what build/index.html contains instead (note that the first if block is entirely missing):
<script type="text/javascript">
console.log("production");var nodeEnv="production";"production"===nodeEnv&&console.log("This is REALLY production!")
</script>