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Object.prototype.valueOf() - JavaScript | MDN
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  6. Object.prototype.valueOf()
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Object.prototype.valueOf()

Baseline Widely available

This feature is well established and works across many devices and browser versions. Its been available across browsers since 2015 ..

valueOf() .

In this article

object.valueOf()

JavaScript valueOf . valueOf ; JavaScript , .

, valueOf , Object. , . , valueOf , :

js
[object Object]

valueOf . , Object.prototype.valueOf(), Object.

valueOf

, valueOf . .

, myNumberType valueOf. valueOf :

js
myNumberType.prototype.valueOf = function () {
  return customPrimitiveValue;
};

, , myNumberType , , JavaScript , .

valueOf JavaScript, , :

js
myNumber.valueOf();

: toString(), String, valueOf. "[object type]". , .

: valueOf

js
var o = new Object();
myVar = o.valueOf(); // [object Object]

Specification
ECMAScript 2027 LanguageSpecification
# sec-object.prototype.valueof

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  2. Object
    1. Object()
    1. Object.assign()
    2. Object.create()
    3. Object.defineProperties()
    4. Object.defineProperty()
    5. Object.entries()
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    7. Object.fromEntries()
    8. Object.getOwnPropertyDescriptor()
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    21. Object.seal()
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    23. Object.values()
    1. Object.prototype.__defineGetter__()
    2. Object.prototype.__defineSetter__()
    3. Object.prototype.__lookupGetter__()
    4. Object.prototype.__lookupSetter__()
    5. Object.prototype.hasOwnProperty()
    6. Object.prototype.isPrototypeOf()
    7. Object.prototype.propertyIsEnumerable()
    8. Object.prototype.toLocaleString()
    9. Object.prototype.toString()
    10. Object.prototype.valueOf()
    1. Object.prototype.__proto__
    2. Object.prototype.constructor
  8. Object/Function
    1. Function.prototype.apply()
    2. Function.prototype.bind()
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    4. Function.prototype.toString()
    5. [Symbol.hasInstance]()
    1. Function.displayName
    2. Function.length
    3. Function.name
    4. prototype
    5. Function.arguments
    6. Function.caller
    1. Object.prototype.__defineGetter__()
    2. Object.prototype.__defineSetter__()
    3. Object.prototype.__lookupGetter__()
    4. Object.prototype.__lookupSetter__()
    5. Object.prototype.hasOwnProperty()
    6. Object.prototype.isPrototypeOf()
    7. Object.prototype.propertyIsEnumerable()
    8. Object.prototype.toLocaleString()
    9. Object.prototype.toString()
    10. Object.prototype.valueOf()
    1. Object.prototype.__proto__
    2. Object.prototype.constructor
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