Edit in JSFiddle

javascript: function showResults() {
    for (var e = 0; e < shots.length; e++) {
        document.write('<img src="' + shots[e] + '"/>\n')
    }
}
var myCanvas = prompt("ID of the canvas you want to capture?");
var myGrabLimit = prompt("How many frames do you want to capture?");
var myGrabRate = prompt("Capture frequency in miliseconds");
var canvas = document.getElementById(myCanvas);
var shots = [];
var grabLimit = myGrabLimit;
var grabRate = myGrabRate;
var count = 0;
var grabber = setInterval(function () {
    count++;
    if (count > grabLimit) {
        clearInterval(grabber);
        showResults()
    }
    var e = canvas.toDataURL("image/png");
    shots.push(e)
}, grabRate);