Function: isNativeFunction()

isNativeFunction(target): boolean

Tell whether a value is a native function, implemented by the JavaScript engine or Node.js rather than in JavaScript: its source, as Function.prototype.toString gives it, is function name() { [native code] }. The built-ins (Math.max, Array) are native, and so are all the bound functions (fn.bind(null)), whatever they bind: the runtime gives them the same source, so a bound function cannot be told apart reliably from a built-in. The functions, the arrow functions and the classes written in JavaScript are not. A function's own toString cannot fake the result. An object whose Object.prototype.toString tag ends with Constructor ([object HTMLElementConstructor], a host object of some environments) is also native.

Parameters

target

any

The value to test, of any type; a value which is neither a function nor an object gives false.

Returns

boolean

true when the value is a native function, false otherwise.

Example

import {isNativeFunction} from 'lakutata/utils'

console.log(isNativeFunction(Math.max), isNativeFunction((): number => 1), isNativeFunction(class Point {}))
//true false false