How to share variables between classes in javascript

Question

I am expanding my JS knowledge by building custom libraries on-top of jQuery/JS and the classes have to interact between each other. I am coming from PHP, so there I could use static variables, but have no idea in JS. Here is an example of what I want:

var A = function() {
    this.myPublicVar = "thisShouldBePrintedFromClassB";
}

A.prototype = {
    showMyVar : function() {alert(this.myPublicVar);} // This gets triggered on direct access.
}

var B = function() {}
B.prototype = {
    // I have no idea how to to access A.myPublicVar
}

Anyone could provide me with simple tutorial or anything?

PS: I have just started to expand my JS knowledge, have used JS/jQuery for easy design purposes (using selectors and building data validators and etc.)

`B` needs to inherit from `A` if you want to access that property. — elclanrs, Apr 05 '13 at 22:22
B.prototype = new A(); something like this read this it may be useful http://stackoverflow.com/questions/15843660/inheritance-within-javascript — Givi, Apr 05 '13 at 22:23
and how should I use multiple classes lets say like in a framework(ie. multiple inheritance) — DaGhostman Dimitrov, Apr 05 '13 at 22:25
The problem is that you're thinking in classes. JavaScript prototype model can sort of imitate class inheritance but not the other way around. Think about modules, that's the JavaScript way. — elclanrs, Apr 05 '13 at 22:27
try this var foo = (function(foo) { // put all code here... }(foo || {})); and you can read about module patterns from here... http://www.adequatelygood.com/JavaScript-Module-Pattern-In-Depth.html — Givi, Apr 05 '13 at 22:32

Kevin Bowersox · Accepted Answer · 2013-04-05T22:34:27.040

4

You can use inheritance to access the variable.

var A = function() {
    this.myPublicVar = "thisShouldBePrintedFromClassB";
}

A.prototype = {
    showMyVar : function() {alert(this.myPublicVar);} // This gets triggered on direct access.
}

var B = function() {}
B.prototype = new A();
B.prototype.print = function(){
  alert(this.myPublicVar);
}

var b = new B();
b.print();

edited Apr 05 '13 at 22:34

answered Apr 05 '13 at 22:24

Kevin Bowersox

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KingKongFrog · Answer 2 · 2013-04-05T22:37:02.077

1

var A = function() {
    this.myPublicVar = "thisShouldBePrintedFromClassB";
}

A.prototype = {
    showMyVar : function() {alert(this.myPublicVar);} // This gets triggered on direct access.
}

var B = function() {}
B.prototype = new A();  //This is what you're missing.

console.log(B.prototype.myPublicVar);

edited Apr 05 '13 at 22:37

answered Apr 05 '13 at 22:23

KingKongFrog

13,946
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How to share variables between classes in javascript

2 Answers2