Preserve variables in a javascript closure function

Question

I am pretty much a novice in javascript programming and i would really need some help/advice.

What i am trying to do: I have a function (or object?!) which looks like this:

var svgInteraction = function (containerId) {
    var svgNamespace = "http://www.w3.org/2000/svg",
        htmlns = "http://www.w3.org/1999/xhtml",
    mathns = "http://www.w3.org/1998/Math/MathML";

    svgInteractions = {};

    svgInteractions[containerId] = "I am " + containerId;
    console.log(svgInteractions);

    return function () {
        console.log(svgInteractions);
    }
};

i initialize a variable like this:

var svg1 = svgInteraction("container_1");
var svg2 = svgInteraction("container_2");

The problem is that, for each initialization of the svgInteraction, the svgInteractions objects reinitialize.

It outputs:

Object { container_1="I am container_1"}
Object { container_2="I am container_2"}

Is there any way to keep old values inside it?

Thank you

alex · Accepted Answer · 2011-10-25 07:23:24Z

1

Don't set it to an empty object each time (svgInteractions = {}) the function is called.

Try this...

var svgInteraction = (function() {

   var svgInteractions = {};

   return function(containerId) {
     // Implementation
   }

})();

Here, svgInteractions is encapsulated but it will also be static for all calls to svgInteraction.

answered Oct 25, 2011 at 7:23

alex

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2 Comments

Gavan Catalin Over a year ago

Thank you. All the implementation code should be inside of return function right? It is like a init() ? Another question: How can i keep independent variables/functions for each initialization? For example, i want a different 'click' function to be executed depending on the container. I was thinking about something like svgInteractions[containerId].clickfunction = function() { ... }

alex Over a year ago

@GavanCatalin Yep, you are correct. Anything you want to be initialised per call should be in the function body.

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