@babel/plugin-transform-react-constant-elements
This plugin can speed up reconciliation and reduce garbage collection pressure by hoisting React elements to the highest possible scope, preventing multiple unnecessary reinstantiations.
Example
In
JSX
const Hr = () => {
return <hr className="hr" />;
};
const WithChildren = (props) => {
return <div className={props.className}>
<hr />
</div>;
}
Out
JSX
var _hr, _hr2;
const Hr = () => {
return _hr || (_hr = <hr className="hr" />);
};
const WithChildren = (props) => {
return <div className={props.className}>
{_hr2 || (_hr2 = <hr />)}
</div>;
}
Deopts
-
Spread Operator
JSX<div {...foobar} />
-
Refs
JSX<div ref="foobar" />
<div ref={node => this.node = node} /> -
Mutable Properties
tip
See https://github.com/facebook/react/issues/3226 for more on this
JavaScript
<div style={{ width: 100 }} />
Installation
- npm
- Yarn
- pnpm
npm install --save-dev @babel/plugin-transform-react-constant-elements
yarn add --dev @babel/plugin-transform-react-constant-elements
pnpm add --save-dev @babel/plugin-transform-react-constant-elements
Usage
With a configuration file (Recommended)
babel.config.json
{
"plugins": ["@babel/plugin-transform-react-constant-elements"]
}
Options
allowMutablePropsOnTags
Array<string>
, defaults to []
If you are using a particular library (like react-intl) that uses object properties, and you are sure that the element won't modify its own props, you can permit objects to be allowed for specific elements.
This will skip the Mutable Properties
deopt.
babel.config.json
{
"plugins": [
[
"@babel/plugin-transform-react-constant-elements",
{ "allowMutablePropsOnTags": ["FormattedMessage"] }
]
]
}
tip
You can read more about configuring plugin options here
Via CLI
Shell
babel --plugins @babel/plugin-transform-react-constant-elements script.js
Via Node API
JavaScript
require("@babel/core").transformSync("code", {
plugins: ["@babel/plugin-transform-react-constant-elements"],
});