CODEWITHSUNDEEP
javascript
coure2011
coure2011

Reputation: 42454

Valid Object Constructors

which of the following are valid object constructors?

1) var m = function(){}
2) m = function(){}
3) m.prototype.constructor = function(){}

Upvotes: 3

Views: 210

Answers (3)

Justin Love
Justin Love

Reputation: 4457

They all appear to be valid statements that declare an empty function, and assign it to different variables.

Every function in Javascript is both an object itself (or f.prototype wouldn't work) and a potential object constructor. Any function may be called with the new Thingy syntax (or perhaps new m in your example). Or it could be called normally - the only special thing new does is set this to an object derived from f.prototype.

A newly created function has a prototype property that contains a newly minted object ({}), which has no properties except a hidden constructor property pointing at the function (it's a circular reference, actually)

It should be true that:

var m = function(){};
m.prototype.constructor == m;

Upvotes: 1

fantactuka
fantactuka

Reputation: 3334

1) var m = function(){}

2) m = function(){}

Are almost same except the first one creates a local scoped function, the second - global. And in order to create an object you can just

var obj = new m();

Upvotes: 0

cllpse
cllpse

Reputation: 21727

You forgot var m = {};

This is called an object literal.

Upvotes: 1

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