What does the Object function in JavaScript do?
For example, what happens when we do Object(1)?
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5 Answers
It forces something to be an object. I've not seen it being used in this way though.
var num = 1;
var obj = Object(num);
alert(typeof num); //displays "number"
alert(typeof obj): //displays "object"
alert(num + "," + obj); //displays "1,1"
The preferred, faster way to create an empty object on which you can put properties and methods on is by using {}. Three possible ways to create an object:
var emptyObj = {};
var emptyObj = new Object();
var emptyObj = new Object; // Object does not need an argument, so this is valid.
3 Comments
Pacerier
heys regarding the third example, is it "standard" and widely supported?
Lekensteyn
@Pacerier: Per "JavaScript: The Definitive Guide", by David Flanagan, 5.10.3: "As a special case, for the new operator only, JavaScript simplifies the grammar by allowing the parentheses to be omitted if there are no arguments in the function call".
Lekensteyn
@Pacerier: Section 5.2.2 (and 5.2.2.1) from EXCMA 262 specification allows
new Object and new Object(). Per 5.2.2: "When Object is called as part of a new expression, it is a constructor that may create an object.". Per 5.2.2.1: "When the Object constructor is called with no arguments or with one argument value, the following steps are taken: [..] 8. Return obj." So, the behavior is the same.From the Mozilla developer site:
The Object constructor creates an object wrapper for the given value. If the value is null or undefined, it will create and return an empty object, otherwise, it will return an object of type that corresponds to the given value.
When called in a non-constructor context, Object behaves identically.
So Object(1) produces an object that behaves similarly to the primitive value 1, but with support for object features like assigning values to properties (Object(1).foo = 2 will work, (1).foo = 2 will not).
Comments
var obj = Object("test");
Creates a String "text", it's pretty similar to
var obj2 = "test";
Notice that the type of obj2 is "String" and of obj1 "Object"
Try this:
<script>
var obj = Object("test");
console.log(obj);
console.log(typeof(obj));
console.log(obj["0"]);
obj2 = "test";
console.log(obj2);
console.log(typeof(obj2));
console.log(obj2["0"]);
</script>
Comments
Creates an object http://www.w3schools.com/js/js_objects.asp
Comments
Object function is a constructor function, all other types(like Array, String, Number) inheritate it.
