In JavaScript, what's the difference between
var x = Object();
and
var x = new Object();
?
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@Babiker: Yep, that's the question I was looking for, but it turns out it's not similar at all.Sasha Chedygov– Sasha Chedygov2010-06-20 19:39:15 +00:00Commented Jun 20, 2010 at 19:39
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1 Answer
This is pulled directly from the ECMAScript specification:
15.2.1 The Object Constructor Called as a Function
When Object is called as a function rather than as a constructor, it performs a type conversion.
15.2.1.1 Object ( [ value ] )
When the Object function is called with no arguments or with one argument value, the following steps are taken:
If value is null, undefined or not supplied, create and return a new Object object exactly as if the standard built-in Object constructor had been called with the same arguments (15.2.2.1).
In Short:
new Object([ value ])Return ToObject(value).
Notes:
[ ] Is A common way to mark a parameter as optional.
ToObject Is a very simple operation that is defined in section 9.9.
5 Comments
Skilldrick
So it called as a function with no arguments what does it do? Convert
undefined to an object?
ChaosPandion
It simply returns the equivalent of calling
new Object().
Sasha Chedygov
@Skilldrick: It would "create and return a new Object object exactly as if the standard built-in Object constructor had been called with the same arguments." So it would be the same as simply saying
new Object().
jigfox
So there is no difference between
Object() and new Object()?ChaosPandion
@Jens - The final result is the same. The only difference being a layer of redirection to the internal method Construct.