JavaScript: Function.prototype

Function.prototype is the value of the property key "prototype" of the Function object.

〔►see JavaScript: Function Object〕

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

Type of Function.prototype is function object.

〔►see JavaScript: Data Types〕

// type of Function.prototype
console.log ( typeof Function.prototype === "function" ); // true
console.log ( Object.prototype.toString.call( Function.prototype ) === "[object Function]" ) // true

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

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

console.log (
 Function.prototype() === undefined ); // true

console.log (
 Function.prototype(3) === undefined );    // true

console.log (
 Function.prototype(3, 4) === undefined ); // true

console.log (
 Function.prototype({}) === undefined ); // true

Parent of Function.prototype is Object.prototype.

// parent of Function.prototype
console.log ( Object.getPrototypeOf ( Function.prototype ) === Object.prototype ); // true

Function.prototype is the parent of all function objects.

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

〔►see JavaScript: Prototype and Inheritance〕

Properties

• Function.prototype.constructor
• Function.prototype.call
• Function.prototype.apply
• Function.prototype.bind
• Function.prototype.toString
• Function.prototype[Symbol.hasInstance] (ES2015)

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Function.prototype.constructor

Function.prototype.constructor

Value is the Function function object.

function f1 () { }
console.log ( f1.constructor === Function ); // true

const f2 = (x => x+1);
console.log ( f2.constructor === Function ); // true

〔►see JavaScript: Function Object〕

〔►see JavaScript: Arrow Function〕

〔►see JavaScript: Property Key "constructor"〕

ECMAScript 2015 §Fundamental Objects#sec-function.prototype.constructor

Function.prototype.call

〔►see JavaScript: Function.prototype.call〕

Function.prototype.apply

〔►see JavaScript: Function.prototype.apply〕

Function.prototype.bind

〔►see JavaScript: Function.prototype.bind〕

Function.prototype.toString

〔►see JavaScript: Function.prototype.toString〕

Function.prototype[Symbol.hasInstance]

〔►see JavaScript: Function.prototype[Symbol.hasInstance]〕

Reference

ECMAScript 2015 §Fundamental Objects#sec-properties-of-the-function-prototype-object