d, which, for most objects without [ ` @@toPrimitive ` ](/en-
US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/toPrimitive) , means
calling its ` valueOf() ` . However, if the object doesn't have a custom `
valueOf() ` method, the base implementation will cause ` valueOf() ` to be
ignored and the return value of ` toString() ` to be used instead.

js

    
    
    +new Date(); // the current timestamp; same as new Date().getTime()
    +{}; // NaN (toString() returns "[object Object]")
    +[]; // 0 (toString() returns an empty string list)
    +[1]; // 1 (toString() returns "1")
    +[1, 2]; // NaN (toString() returns "1,2")
    +new Set([1]); // NaN (toString() returns "[object Set]")
    +{ valueOf: () => 42 }; // 42
    

##  Specifications

Specification  
---  
[ ECMAScript Language Specification  
#  sec-object.prototype.valueof
](https://tc39.es/ecma262/multipage/fundamental-objects.html#sec-
object.prototype.valueof)  
  
##  Browser compatibility

BCD tables only load in the browser  with JavaScript enabled. Enable
JavaScript to view data.

##  See also

  * [ ` Object.prototype.toString() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/toString)
  * [ ` parseInt() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt)
  * [ ` Symbol.toPrimitive ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/toPrimitive)

##  Help improve MDN

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