83 lines
1.5 KiB
Markdown
83 lines
1.5 KiB
Markdown
# babel-plugin-transform-react-constant-elements
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Hoists element creation to the top level for subtrees that are fully static, which reduces both allocations and calls to `React.createElement`. More importantly, it tells React that the subtree hasn't changed so React can completely skip it when reconciling.
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This transform **should be enabled only in production** (e.g., just before minifying your code) because although it improves runtime performance, it makes warning messages more cryptic.
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## Example
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**In**
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```js
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const Hr = () => {
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return <hr className="hr" />;
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};
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```
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**Out**
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```js
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const _ref = <hr className="hr" />;
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const Hr = () => {
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return _ref;
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};
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```
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**Deopts**
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- **Spread Operator**
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```js
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<div {...foobar} />
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```
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- **Refs**
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```js
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<div ref="foobar" />
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<div ref={node => this.node = node} />
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```
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- **Composite Components**
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```js
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const ComponentA = () => <div><MyCustomComponent /></div>;
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```
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## Installation
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```sh
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npm install --save-dev babel-plugin-transform-react-constant-elements
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```
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## Usage
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### Via `.babelrc` (Recommended)
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**.babelrc**
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```json
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{
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"plugins": ["transform-react-constant-elements"]
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}
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```
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### Via CLI
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```sh
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babel --plugins transform-react-constant-elements script.js
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```
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### Via Node API
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```javascript
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require("babel-core").transform("code", {
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plugins: ["transform-react-constant-elements"]
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});
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```
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## References
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* [[facebook/react#3226] Optimizing Compiler: Reuse Constant Value Types like ReactElement](https://github.com/facebook/react/issues/3226)
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