JavaScript: Function.prototype

By Xah Lee. Date: . Last updated: .

Function.prototype is the value of the property key "prototype" of the function Function. [see Function Object]

console.log( Function.hasOwnProperty ( "prototype" ) );

Type

Type of Function.prototype is function object.

console.log( typeof Function.prototype === "function" );

Function.prototype(
) is not useful. You could call Function.prototype(
). It takes any number of arguments, and always return undefined.

// Function.prototype() takes any arg, return undefined

console.log(Function.prototype() === undefined);
console.log(Function.prototype(3) === undefined);
console.log(Function.prototype(3, 4) === undefined);
console.log(Function.prototype({}) === undefined);

Parent

Parent of Function.prototype is Object.prototype .

console.log( Reflect.getPrototypeOf ( Function.prototype ) === Object.prototype );

Purpose

Function.prototype is the parent of all function objects.

console.log( Reflect.getPrototypeOf ( function f () {} ) === Function.prototype );
console.log( Reflect.getPrototypeOf (x => 3) === Function.prototype );

[see Prototype and Inheritance]

Properties

Value Properties

Function Properties

JavaScript Function

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