CODEWITHSUNDEEP
javascriptconstructor
Joel A. Villarreal Bertoldi
Joel A. Villarreal Bertoldi

Reputation: 8017

JavaScript constructors

I do not understand quite completely how to apply constructors on this object creation method:


var MyObject = {
   ...
};

I know that you can do:


var MyObject = new Object();
MyObject.prototype.constructor = function(props)
{
  ...
}

or...


function MyObject(prop1, prop2)
{
 this.prop1 = prop1;
 ...
}

Can I do something like this?


var MyObject = {
   MyObject: function(prop1, prop2)
   {
     ...
   }
}

Upvotes: -1

Views: 399

Answers (3)

Nicole
Nicole

Reputation: 33197

No, you can't, that would simply create a (static) method on MyObject -- MyObject.MyObject. In JavaScript, a constructor is the class. Class methods and properties are created either inside the constructor using this. or by adding to the prototype (outside of the constructor) using MyClass.prototype.. You can think of "objects" in JavaScript as static classes.

Upvotes: 0

Gabriel McAdams
Gabriel McAdams

Reputation: 58261

var MyObject = new Object();
MyObject.prototype.constructor = function(props)
{
    ...
}

is the same as 

var MyObject = {};
MyObject.prototype.constructor = function(props)
{
    ...
}

Upvotes: 0

Gabe
Gabe

Reputation: 50493

Example from here

Creating constructors

To write your own constructors, you use the this keyword within the constructor to refer to the newly-created object. The constructor initializes the object.

In the example below:

The make7Table constructor creates a multiplication table for number 7 The size property is introduced to keep track of the number of elements The value of each element is initialized

function make7Table(numElements)
{
    this.size = numElements;
    var cnt;
    for(cnt = 0; cnt < numElements; cnt++)
    {
        this[cnt] = cnt*7;
    }
}

// Use the constructor to create and initialize an array.
myArray = new make7Table(10);
document.write(myArray[5]);
document.write("This table has " + myArray.size + " elements");

To run the code, paste it into JavaScript Editor, and click the Execute button. myArray[5] retrieves the element with the value of 5*7 = 35.

Upvotes: 0

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