@babel/plugin-transform-spread
Example
In
var a = ['a', 'b', 'c'];
var b = [...a, 'foo'];
var c = foo(...a);
Out
var a = ['a', 'b', 'c'];
var b = a.concat(['foo']);
var c = foo.apply(void 0, a);
Installation
npm install --save-dev @babel/plugin-transform-spread
Usage
With a configuration file (Recommended)
Without options:
{
"plugins": ["@babel/plugin-transform-spread"]
}
With options:
{
"plugins": [
["@babel/plugin-transform-spread", {
"loose": true
}]
]
}
Via CLI
babel --plugins @babel/plugin-transform-spread script.js
Via Node API
require("@babel/core").transform("code", {
plugins: ["@babel/plugin-transform-spread"]
});
Options
loose
boolean, defaults to false.
In loose mode, all iterables are assumed to be arrays.
Loose mode preserves "holes" when spreading an array (for example, [ ...Array(2) ] produces [ (hole), (hole) ]). Set loose to false to avoid this behaviour.
You can read more about configuring plugin options here
allowArrayLike
boolean, defaults to false
Added in: v7.10.0
This option allows spreading array-like objects as if they were arrays.
An array-like object is an object with a length property: for example, { 0: "a", 1: "b", length: 2 }. Note that, like real arrays, array-like objects can have "holes": { 1: "a", length: 3 } is equivalent to [ (hole), "a", (hole) ].
While it is not spec-compliant to spread array-like objects as if they were arrays, there are many objects that would be iterables in modern browsers with Symbol.iterator support. Some notable examples are the DOM collections, like document.querySelectorAll("img.big"), which are the main use case for this option.
Please note that Babel allows spreading arguments in old engines even if this option is disabled, because it's defined as iterable in the ECMAScript specification.