javascript object reference by array

Question

How can I refer to an object element dynamically during a loop by using an array, something like this:

var obj = {};
var lvl = ['x','y','z'];
var ol = [];
for (var l in lvl){
 ol.push( lvl[l] )
 obj[ol] = 'someval'
}

so where the reference may be obj[x][y][z] so each time the loop iterates, an additional key reference is appended, but I do not know how many levels there will be.

Not sure if I have explained that very well ?!

• Mritunjay: are you sure you want this? obj[ol] this will keep an array as key of object. or do you want obj[ol[l]].
• crankshaft: I am looking to dynamically add [] each time the loop iterates, so at the end of this example the refernce would be obj[x][y][z].
• yoleg: Ok so just to be clear you want obj[x][y][z] = "someval". Essentially nesting object keys?
• crankshaft: yes, I am looping through an array and I need to be able to push to or add key-value pairs to a nested object
• yoleg: did any of the answers match what you were looking for?

Answer 1

Based on how you answered my comment I believe this code will provide the nested object structure you are looking for.

var obj = {};
var lvl = ['x','y','z'];
var ol = {};
for (var i = 0; i < lvl.length; i++){
 obj[i] = {}; 
 ol = obj[key];
}

• slebetman: the var key in lvl bit is wrong because it would give you 0,1,2,length not x,y,z. Found out the hard way when testing my own answer. Use foreach or a regular for(x=0;x<lvl.length;x++) loop.
• slebetman: Alternatively, you can change lvl to be {x:'',y:'',z:''} instead of an array.

Answer 2

You mean you want someval to be the value of obj.x.y.z? You can always refer to the newly created levels using a variable:

var obj = {};
var levels = ['x','y','z'];
var pointer = obj;
for (var l=0; l<levels.length; l++) {
 key = levels[l];
 if (l < levels.length-1) { // if not last element
 pointer[key] = {};
 pointer = pointer[key];
 }
 else { // if last element
 pointer[key] = 'someval';
 }
}
console.log(obj); // should log {x:{y:{z:"someval"}}}

• slebetman: OK. Finally got it working. Remember, variables are references only when they're pointing to arrays or objects. But they're values once you assign a string or number to them.. arrrrgh...