Question

I need to create javascript objects that base on user defined number. So if user defines 20, then I need to create 20 variables.

var interval_1=0, interval_2=0, interval_3=0, interval_4=0, interval_5=0... interval_20=0;

how do I do it so the name of the object can be dynamically created?

for (i=0; i<=interval; i++){
    var interval_ + i.toString() = i;
}

Answer 1

Use an array:

var i, count, interval = [];

// user defines count, 20 for example
count = 20;

for (i = 0; i < count; i++) {
    interval.push(i);
}

// interval[0] === 0
// interval[19] === 19
// interval.length === 20

Note, this starts the index at 0 and goes up to count – 1. Do not use i <= count unless you start i at 1.

Here is a jsFiddle to illustrate. Hit F12 to open dev tools in most browsers and look at console, or change console.log() to alert().

Link: http://jsfiddle.net/willslab/CapBN/1/

Alternatively, you could setup a single object with properties for each value:

var i, count, intervals = {};

count = 20;

for (i = 0; i < count; i++) {
    intervals["interval_" + i] = i;
}

//intervals.interval_0 === 0
//intervals.interval_19 === 19)

Link: http://jsfiddle.net/willslab/EBjx7/2/