What is the differnce between following two?
obj = new Object();
OR
obj = {};
In my code am asked to replace first notation with second one and the code is huge.Will replacing it cause any problem?
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4 Answers
According to JavaScript Patterns book, using a built-in constructor (obj = new Object();) is an anti pattern for several reasons:
- it's longer to type than literal (obj = {};)
- literal is preferred because it emphasizes that objects are mutable hashes
- scope resolution - possibility that you have created your own (local) constructor with the same name (interpreter needs to look up the scope chain)
Comments
I will answer the second question:
Will replacing it cause any problem?
Nope, it won't cause any problem.
If you have for example those lines:
var obj = new Object("a");
//...code...
obj = new Object("b");
//...code...
Changing to this will have same result and no impacts:
var obj = { "a": 1 };
//...code...
obj = { "b": 2 };
//...code...
By assigning the variable with the = you're overwriting whatever it contained with the new value.
Comments
There is no difference. The former uses the Object constructor, whereas the latter is a literal, but there will be no difference in the resulting objects.
4 Comments
Jakob
Unless someone has redefined
Object somewhere in the code ;)
icktoofay
@Jakob: I suppose you're right, but I doubt anyone would do that.
jslearner
@jakob: i am reinitializing same object many times uisng new Obejct.Is it fine to replace that too with {} .Meaning same object refrace i want to point to new object
Jakob
Yes, that is fine. My comment was mostly a joke, but also a hint that using
Object is a bad idea, since it follows the normal scope resolution rules of the language. The only thing that could cause trouble for you would be if someone has been stupid enough to write something like: Object = function() { alert('Haha, Object is not what you think it is!'); }Greetings Objects in JavaScript
1- var obj = { key1 : value1 , key2Asfunction : funciton1(){} };
obj.key1;
obj.key2Asfunction();
2- var obj = function()
{
this.obj1 = value1 ;
this.function1 = function(){};
}
var ob = new obj();
ob.obj1;
ob.function1();
if you need how to create the structure of the jquery frame work too i can help
Regrads :)
2 Comments
Felix Kling
This is does not really seem to answer the question at hand.
Marwan
well i though it was helping but i forgot to mention things about both ways. thanx Felix