CODEWITHSUNDEEP
javascriptoopd3.js
Sam Selikoff
Sam Selikoff

Reputation: 12694

How do I pass around data within an object?

I have a chart object, with methods draw and update. See this (non-working) fiddle.

draw does a lot of things with the object's properties, and at the end, draws a chart. At this point, I am able to define an update function, since all the data that was processed by draw is there. But then I can't call update from outside the scope.

How do I define the update method as a completely separate method so I can call it from outside the object, but have it be able to reference data within the draw method?

Update: I've posted some semi-pseudo code.

Upvotes: 0

Views: 85

Answers (4)

Munish Poonia
Munish Poonia

Reputation: 838

You can do something like:

var TestObject = function () {
    var a, b;
    this.draw = function (aVal, bVal) {
        a = aVal;
        b = bVal;
    }
    this.update = function () {
        console.info("a = " + a + " | b = " + b);
    }
}

Then you can call as:

var obj = new TestObject();
obj.draw(3, 4);
obj.update();

jsfiddle at - http://jsfiddle.net/poonia/XAm52/

Upvotes: 0

Jamiec
Jamiec

Reputation: 136104

like this perhaps:

function MyChart(x,y){

   this.draw = function(){
      console.log('draw chart using variables x:' + x + ' y:' + y);

      return {
          update: function(){
               console.log('update chart using variables x:' + x + ' y:' + y);
          }
      }
   }
}

usage:

 var chart = new MyChart(123,987);
 var drawResult = chart.draw();
 drawResult.update();

Live example: http://jsfiddle.net/c9TeU/

Upvotes: 3

fmsf
fmsf

Reputation: 37137

Since you don't give us much information I'll try to guess what you want. I assume you want this:

var updateFunction = function(){
   update();
};

return updateFunction();

But you can just directly return update; In javascript functions can be stored in variables, so if you can pass a variable to outside the scope you can also pass a function

Upvotes: 0

Florian Margaine
Florian Margaine

Reputation: 60727

function update(obj) {
}

var obj = {
    function draw() {
        update(this); // works
    }
};

You might want to read about Javascript Functions and function scope, and about lexical scope.

Upvotes: 1

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