Failing accessing array which is property of an object in Javascript

Question

I'm trying to access array which is property of an object, but I can only access letters from property name.

var obj = {};

obj.line0=[0,0];
obj.line1=[0,50];

var pointsLenght = 8;

//things above are just test case sandbox representing small amount of real data

var createPoints = function(obj){
    var i;
    for(var x in obj){
        if (obj.hasOwnProperty(x)) {
            for (i=0;i<pointsLenght;i++){
                if (i%2==0){
                    x[i]=i*50;
                }
                else {
                    x[i]=x[1];
                }
                console.log(i+" element of array "+x+" is equal "+x[i]);
            }
        }
    }
    return obj;
}

And this is what I get in console (Firefox 47.0):

0 element of array line0 is equal l
1 element of array line0 is equal i
2 element of array line0 is equal n
3 element of array line0 is equal e
4 element of array line0 is equal 0
5 element of array line0 is equal undefined
6 element of array line0 is equal undefined
7 element of array line0 is equal undefined

How to access array?

For clarification what are expected results?

charlietfl
– charlietfl

2016-07-16 17:54:00 +00:00
Commented Jul 16, 2016 at 17:54 — charlietfl
– charlietfl, Commented Jul 16, 2016 at 17:54

Rajaprabhu Aravindasamy · Accepted Answer · 2016-07-16 17:51:26Z

2

You are accessing the property name, that is a string. ("line0" and "line1")

For accessing the array belongs to that property name, Just write your code like,

var createPoints = function(obj){
    var i;
    for(var x in obj){
        if (obj.hasOwnProperty(x)) {
            for (i=0;i<pointsLenght;i++){
                if (i%2==0){
                    obj[x][i]=i*50;
                    //obj[x] will give you the array belongs to the property x
                }
                else {
                    obj[x][i]= obj[x][1];
                    //obj[x] will give you the array belongs to the property x 
                }
                console.log(i+" element of array "+x+" is equal "+ obj[x][i]);
            }
        }
    }
    return obj;
}

answered Jul 16, 2016 at 17:51

Rajaprabhu Aravindasamy

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1 Comment

jazzgot Over a year ago

Your solution works perfectly, I just chose Ayan answer as a little bit more elegant.

Ayan · Accepted Answer · 2016-07-16 17:58:32Z

1

Operations need to be done obj[x]. Please Check with the code:

var obj = {};

obj.line0 = [0, 0];
obj.line1 = [0, 50];

var pointsLenght = 8;

//things above are just test case sandbox representing small amount of real data

var createPoints = function(obj) {
  var i, elem;
  for (var x in obj) {
    if (obj.hasOwnProperty(x)) {
      elem = obj[x];
      for (i = 0; i < pointsLenght; i++) {
        elem[i] = (i % 2 == 0) ? (i * 50) : elem[1];
        console.log(i + " element of array " + elem + " is equal " + elem[i]);
      }
    }
  }
  return obj;
}
createPoints(obj);

edited Jul 16, 2016 at 17:58

answered Jul 16, 2016 at 17:53

Ayan

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