javascript setInterval in array

Question

I created an array and inserted a setInterval in it, but tmp[0] doesn't work

tmp = new Array();
v = new Array();
for(i=0; i<2; i++){
j = 0;
tmp[i] = setInterval("if(j<10+(i*5)){alert(i+' '+j);j++;}else{clearInterval(tmp[i])}", 1000);
}

What did you expect to happen? – Blazemonger Aug 30 '11 at 13:12 — Blazemonger, Aug 30 '11 at 13:12
It should alert: "0 0" "1 0" "0 1" "1 1" "0 2" "1 2" ... – R. 久蔵 Aug 30 '11 at 13:18 — R. 久蔵, Aug 30 '11 at 13:18
@キューゾリファイ see the update to my answer.. – Naftali Aug 30 '11 at 13:26 — Naftali, Aug 30 '11 at 13:26

Naftali · Accepted Answer · 2011-08-30T13:25:46.887

5

Do Not use eval. Try this:

var tmp = new Array();
var v = new Array();
for (i = 0; i < 2; i++) {
    var j = 0;
    tmp[i] = setInterval(function () {
        if (j < 10 + (i * 5)) {
            alert(i + ' ' + j);
            j++;
        } else {
            clearInterval(tmp[i])
        }
    }, 1000);
}

Fiddle: http://jsfiddle.net/FKEL6/ (it is annoying with the popups, just so you are aware.)

This might do what you want it to do:

var tmp = new Array();
var v = new Array();
var i = 0;
for (i = 0; i < 2; i++) {
    createTmp(i);
}

function createTmp(p){
    var j = 0;
    tmp[p] = setInterval(function () {
        if (j < 10 + (p * 5)) {
            alert(p + ' ' + j);
            j++;
        } else {
            clearInterval(tmp[p])
        }
    }, 1000);
}
console.log(tmp);

Fiddle: http://jsfiddle.net/FKEL6/5/ (also has annoying alerts)

edited Aug 30 '11 at 13:25

answered Aug 30 '11 at 13:12

Naftali

144,921
39
244
303

OP isn't using eval, they're using the deprecated form of `setInterval` by passing a string. – zzzzBov Aug 30 '11 at 13:13
1

@キューゾリファイ what does that mean `it doesnt run`? what do you want it to do? – Naftali Aug 30 '11 at 13:17
Using a function creates another problem: scope. – Felix Kling Aug 30 '11 at 13:21
@キューゾリファイ i will always be 2 because it is a global variable... and you increased it in the loop. – Naftali Aug 30 '11 at 13:22
@キューゾリファイ I believe this might do what you want it to do: http://jsfiddle.net/FKEL6/5/ – Naftali Aug 30 '11 at 13:24
Why are you using `new Array();` instead of `[]`? Shouldn't you should show a novice the best practices, if any? – David G Aug 30 '11 at 13:41
@David -- why do you assume that *that* is the `best practice`? – Naftali Aug 30 '11 at 13:47
@David -- http://stackoverflow.com/questions/2517032/advantages-of-using-over-new-array-in-javascript there is **no** difference when it is empty... – Naftali Aug 30 '11 at 13:49

score 0 · Answer 2 · answered Aug 30 '11 at 13:18

0

The output of such a thing is:

etc, which is correct. It stops when j < 20.

But at the end your timer is still going on and all you are doing is calling clearInterval(tmp[2]) over and over, twice a second.

answered Aug 30 '11 at 13:18

Simon Sarris

62,212
13
141
171

javascript setInterval in array

2 Answers2