@babel/plugin-proposal-object-rest-spread
NOTE: This plugin is included in @babel/preset-env, in ES2018
Example
Rest Properties
JavaScript
let { x, y, ...z } = { x: 1, y: 2, a: 3, b: 4 };
console.log(x); // 1
console.log(y); // 2
console.log(z); // { a: 3, b: 4 }
Spread Properties
JavaScript
let n = { x, y, ...z };
console.log(n); // { x: 1, y: 2, a: 3, b: 4 }
Installation
- npm
- Yarn
- pnpm
pnpm add --save-dev @babel/plugin-proposal-object-rest-spread
Usage
With a configuration file (Recommended)
babel.config.json
{
"plugins": ["@babel/plugin-proposal-object-rest-spread"]
}
Via CLI
Shell
babel --plugins @babel/plugin-proposal-object-rest-spread script.js
Via Node API
JavaScript
require("@babel/core").transformSync("code", {
plugins: ["@babel/plugin-proposal-object-rest-spread"],
});
Options
By default, this plugin will produce spec compliant code by using Babel's objectSpread helper.
loose
boolean, defaults to false.
Enabling this option will use Babel's extends helper, which is basically the same as Object.assign (see useBuiltIns below to use it directly).
⚠️ Consider migrating to the top level setSpreadProperties assumption.
babel.config.json
{
"assumptions": {
"setSpreadProperties": true
}
}
Please keep in mind that even if they're almost equivalent, there's an important difference between spread and Object.assign: spread defines new properties, while Object.assign() sets them, so using this mode might produce unexpected results in some cases.
For detailed information please check out Spread VS. Object.assign and Assigning VS. defining properties.
useBuiltIns
boolean, defaults to false.
Enabling this option will use Object.assign directly instead of the Babel's extends helper.
Example
.babelrc
JSON
{
"assumptions": {
"setSpreadProperties": true
},
"plugins": [
["@babel/plugin-proposal-object-rest-spread", { "useBuiltIns": true }]
]
}
In
JavaScript
z = { x, ...y };
Out
JavaScript
z = Object.assign({ x }, y);
You can read more about configuring plugin options here
References
- Proposal: Object Rest/Spread Properties for ECMAScript
- Spec
- Spread VS. Object.assign
- Assigning VS. defining properties
更多建议: