@babel/runtime

@babel/runtime is a library that contains Babel modular runtime helpers.

Installation​

npm install --save @babel/runtime

yarn add @babel/runtime

pnpm add @babel/runtime

bun add @babel/runtime

See also: @babel/runtime-corejs2.

Usage​

This is meant to be used as a runtime dependency along with the Babel plugin @babel/plugin-transform-runtime. Please check out the documentation in that package for usage.

Why​

Sometimes Babel may inject some code in the output that is the same across files, and thus can be potentially re-used.

For example, with the class transform (without loose mode):

classCircle{}

turns into:

function_classCallCheck(instance,Constructor){
//...
}

varCircle=functionCircle(){
_classCallCheck(this,Circle);
};

this means every file that contains a class would have the _classCallCheck function repeated each time.

With @babel/plugin-transform-runtime, it would replace the reference to the function to the @babel/runtime version.

var _classCallCheck =require("@babel/runtime/helpers/classCallCheck");

varCircle=functionCircle(){
_classCallCheck(this,Circle);
};

@babel/runtime is just the package that contains the implementations of the functions in a modular way.