Asynchronous for loop with Javascript

Question

I have this code that I need to convert to async loop since obviously this code for-loop will block the UI/Browser:

    $wnd.mainbuff = [];
    $wnd.update = setInterval(function(){
            // fetches everything in the buffer (csv), including old data
            var temp = $wnd.Recorder.audioData().toString();
            var arr = temp.split(',');
            // so, copy new elements only (must be async) 
            for (var i=$wnd.mainbuff.length; i < arr.length; i++) {
                console.log(arr[i]);
                $wnd.mainbuff[i] = arr[i];  
            }
        }
    ,25)

Take a look at here : stackoverflow.com/questions/6998330/… — Mustafa Genç
– Mustafa Genç, Commented Oct 29, 2012 at 12:07

Bergi · Accepted Answer · 2012-10-29 12:24:40Z

Turn your loop into an equivalent recursive function. It then will be easy to use setTimeout when calling itself.

$wnd.mainbuff = [];
$wmd.curTimerId = null;
$wnd.update = function() {
    var start = Date.now();
    // fetches everything in the buffer (csv), including old data
    //                             doesn't sound good ^^^^^^^^
    var temp = $wnd.Recorder.audioData().toString();
    var arr = temp.split(',');
    // so, copy new elements only
    function processOne(i, callback) {
        if (i < arr.length) {
            console.log(arr[i]);
            $wnd.mainbuff[i] = arr[i];
            setTimeout(function(){processOne(i+1, callback);}, 0);
        } else
            callback();
    }
    processOne($wnd.mainbuff.length, function() {
        setTimeout($wnd.update, 25- (Date.now()-start));
    });
}

Soroush Khosravi · Accepted Answer · 2012-10-29 12:05:44Z

Try this:

$wnd.mainbuff = [];
function async(arr, wnd, currentIndex) {
    console.log(arr[currentIndex]);
    wnd.mainbuff[currentIndexi] = arr[currentIndexi];
}
$wnd.update = setInterval(function(){
        // fetches everything in the buffer (csv), including old data
        var temp = $wnd.Recorder.audioData().toString();
        var arr = temp.split(',');
        // so, copy new elements only (must be async)
        for (var i=$wnd.mainbuff.length; i < arr.length; i++) {
            async(arr, $wnd, i);
        }
    }
,25)

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