CODEWITHSUNDEEP
javascript
Alexander Abramovich
Alexander Abramovich

Reputation: 11438

"Class" constants and constructor: how to implement?

I would like to have something like this implemented in javasript please:

var hat = new Hat(Hat.Color.RED, Hat.Size.MEDIUM);

How can I do it please (tried to mess with function prototype but with a little success)?

Upvotes: 1

Views: 2887

Answers (3)

Bergi
Bergi

Reputation: 664454

Hat will be a constructor function:

function Hat(color, size) {
    this.id = "X"+color+size; // or anything else
}

On the prototype are "methods" for Hat instances:

Hat.prototype.raise = function() {
    ...
};

But the constants are properties of the Function object:

Hat.Color = {
    RED: "F00",
    GREEN: "0F0",
    ...
};
Hat.Size = {
    MEDIUM: 0,
    LARGE: 1,
    ...
};

If your library implements the "extend" function correctly (nothing special on constructors), this should also work:

Object.extend(Hat, {
    Color: {RED: "F00", GREEN: "0F0", ...},
    Size: = {MEDIUM: 0, LARGE: 1, ...},
});

Upvotes: 5

sohaibbbhatti
sohaibbbhatti

Reputation: 2682

This is the functional inheritance way. It distinguishes between private and publci methods and variables.

var Hat = function (color, size) {
  var that = {};
  that.Color = { RED: 'abc'};  // object containing all colors
  that.Size = { Medium: 'big'}; // object containing all sizes
  that.print = function () {
    //I am a public method
  };
  // private methods can be defined here.
  // public methods can be appended to that.
  return that;  // will return that i.e. all public methods and variables
}

Upvotes: 1

Peter Olson
Peter Olson

Reputation: 142921

You can do that if you create a Hat constructor function like this:

function Hat(color, size) {
  this.color = color;
  this.size = size;
}
Hat.Color = {
  RED: "#F00",
  GREEN: "#0F0",
  BLUE: "#00F"
};
Hat.Size = {
  SMALL: 0,
  MEDIUM: 1,
  LARGE: 2
}

You can then create a new Hat and get its properties

var hat = new Hat(Hat.Color.RED, Hat.Size.MEDIUM);
var hatColor = hat.color; // "#F00"

Upvotes: 6

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