why every javascript object has constructor property?

Question

Just trying to understand why every JavaScript object has a constructor property.

Is there any use of constructor property because object is already created?

var MyFunc = function (name){this.name=name}

var instance = new MyFunc("myclass");

now instance has a constructor property which has reference to MyFunc itself. What is use of having constructor property on instance?

score 1 · Answer 1 · answered Oct 03 '14 at 12:32

It is (much) more complicated than that : no object, in, JS has a constructor property by default, but their prototype (if the object has a prototype) have one.

Also, be careful : the constructor references a function, but this prototype property is not read-only, so one can easily change the property, therefore do not rely on it.

score 0 · Answer 2 · answered Oct 03 '14 at 12:25

0

Does this answer your question ?

var dog1= {"a":1}

function Dog ()
{

}


dog2= new Dog();

console.log(dog1.constructor) //function Object() { [native code]...
console.log(dog2.constructor) //function Dog()...

Sometimes you need to know how object was created. ( not to mention that prototype is a constructor property)

answered Oct 03 '14 at 12:25

Royi Namir

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We can use instanceof? – Gaurav Singla Oct 03 '14 at 12:27
@GauravSingla http://stackoverflow.com/questions/18172902/difference-between-instanceof-and-constructor-property – Royi Namir Oct 03 '14 at 12:28
I understood the difference. Still why there is need of constructor property. Do we really need to compare constructors? – Gaurav Singla Oct 03 '14 at 12:33
@GauravSingla If you wanted to modify `Dog.prototype`, but you only had access to the `dog2` instance, you could access `Dog.prototype` with `dog2.constructor.prototype`. – apsillers Oct 03 '14 at 13:09

why every javascript object has constructor property?

2 Answers2