Name
Object.valueOf() — the primitive value of the specified object
Synopsis
object
.
valueOf
()
Returns
The primitive value associated with the
object
, if any. If there is no value
associated with object
, returns the
object itself.
Description
The valueOf()
method of an
object returns the primitive value associated with that object, if
there is one. For objects of type Object, there is no primitive
value, and this method simply returns the object itself.
For objects of type Number, however, valueOf()
returns the primitive numeric
value represented by the object. Similarly, it returns the primitive
boolean value associated with a Boolean object and the string
associated with a String object.
It is rarely necessary to invoke the valueOf()
method yourself. JavaScript does
this automatically whenever an object is used where a primitive
value is expected. In fact, because of this automatic invocation of
the valueOf()
method, it is
difficult to even distinguish between primitive values and their
corresponding objects. The typeof
operator shows you the difference between strings and String objects
for example, but in practical terms, you can use them equivalently
in your JavaScript code.
The valueOf()
methods of
the Number, Boolean, and String objects convert these wrapper
objects to the primitive values they represent. The Object()
constructor performs the opposite operation when invoked with a number, boolean, or string argument: it wraps the primitive value in an appropriate object wrapper. JavaScript ...
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