CODEWITHSUNDEEP
javascript
Joe.wang
Joe.wang

Reputation: 11793

new Function vs new Function()

I saw below being used in the javascript.

var t = new Function;//what does it mean?
var t1 = new Function();

I also read Function in MDN. doesn't found any usage like this.

I knew Function is build-in object in the js. so I did some test for it . found the usage to object is not allowed. why?

    var apple = {
                type: "macintosh",
                color: "red",
                getInfo: function () {
                    return this.color + ' ' + this.type + ' apple';
                }
            }
            var t3 = new apple;//Uncaught TypeError: object is not a function index.html:58
(anonymous function)

What does it mean for new Function without brackets? thanks.

Upvotes: 1

Views: 133

Answers (4)

Kushal
Kushal

Reputation: 1360

var a = new Function

this means you have created an empty anonymous function and both new Function and new Function() are the same if you do not provide the body of the function params

Also apple is an object so can't instantiate it.

Upvotes: 2

Arun Chandran Chackachattil
Arun Chandran Chackachattil

Reputation: 3362

The Function constructor(new Function/new Function()) creates a new Function object. In JavaScript every function is actually a Function object.

Both (new Function/new Function()) are same in java script

Please checkout Function

Upvotes: 1

kriznaraj
kriznaraj

Reputation: 484

Function is a constructor for creating an Object of type Function. u can create new object either one of these ways,

obj = new Function

or

obj = new Function()

The same way, If u have any constructor of ur own type u could do the same. Let's say u have some Constructor of Car. u can create new Car in either one of these ways,

myCar = new Car or myCar = new Car()

But, In ur case apple is constant object. u can not create new object using that. If u want u can have Apple Constructor as following,

function Apple(type, color) {
 this.type = type;
 this.color = color;
}

And then u could do what u actually wanted,

 var t3 = new Apple("macintosh", "red");

Upvotes: 1

axelduch
axelduch

Reputation: 10849

new Function is the same as new Function() your problem here is independent.

apple is a literal object, not a function, so you can't instanciate it, with or without brackets.

Upvotes: 2

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