CODE EXAMPLE FOR JAVASCRIPT

javascript loop through array backwards

function key(event){

    if (event.which == 13){
        if (rw == 0){

            fid = f();
            rw = setInterval(run, 100);
            rs.play();
            bw = setInterval(b,100);
            sw = setInterval(updateScore, 100);
            fw = setInterval(move, 100);
        }
    }
if (event.which == 32){
    if (jw == 0) {
        clearInterval(rw);
        rs.pause();
        rw = -1;

        jw = setInterval(jump, 100);
        js.play();
    }
    }
}

var rs = new Audio("run.mp3");
rs.loop = true;
var js = new Audio("jump.mp3");
var ds = new Audio("dead.mp3");

var fid = 0;
var a = 700;

function f(){
    for (var y = 0; y < 10; y++){
        var i= document.createElement("img");
        i.src = "flame (1).gif";
        i.className = "f";
        i.style.marginLeft= a + "px";
        a = a + 500;
        i.id = "d" + y;
        document.getElementById("b").appendChild(i);
    }
}
var rw = 0;
var r = 1;

function run(){
    var rimg = document.getElementById("girl");
    r = r + 1;
    if (r == 9){
        r = 1;
    }
    rimg.src = "Run (" + r +").png";
}
var bw = 0;
var t = 0;
function b(){
    t = t -20;
    document.getElementById("b").style.backgroundPositionX = t + "px";
}
var sw = 0;
var u = 0;
function updateScore(){
    u = u +10;
    document.getElementById("score").innerHTML = u;
}

var fw = 0;
function move(){
    for (var y = 0; y < 10; y++){
        var z = getComputedStyle(document.getElementById("d" + y));
        var p = parseInt(z.marginLeft);
        p = p -20;
        document.getElementById("d" + y).style.marginLeft = p + "px";
        // alert(p);
        // 160   40
        //280
        if (p <= 140 & p >=60){
            if (mt > 300){
                clearInterval(rw);
                rs.pause();
                clearInterval(jw);
                jw = -1;
                clearInterval(sw);
                clearInterval(bw);
                clearInterval(fw);

                dw = setInterval(dead, 100);
                ds.play();
            }
        }
    }
}

var jw = 0;
var j = 1;
var mt = 390;
function jump(){
    var jimg = document.getElementById("girl");

    if (j <=6){
        mt = mt -30;
    }
    jimg.style.marginTop = mt + "px"; 
    j = j + 1;

    if (j == 13){
        j = 1;
        clearInterval(jw);
        jw = 0;
        rw = setInterval(run,100);
        rs.play();
        if(fid == 0){
            fid = f();
        }
        if(bw == 0){
            bw = setInterval(b,100);
        }
        if(sw == 0){
            sw = setInterval(updateScore,100);
        }
        if(fw == 0){
            fw = setInterval(move,100);
        }
    }
    jimg.src = "jump(" + j +").png"; 

}
var ds = new Audio("dead.mp3");
var d = 0;
function dead(){
    var dimg = document.getElementById("girl");
    d = d + 1;
    if (d == 11){
        d = 10;
        dimg.style.marginTop = "360px";  // boy margin top in css
        document.getElementById("end").style.visibility = "visible";
        document.getElementById("endscore").innerHTML = u;
    }
    dimg.src = "Dead(" + d +").png";
}
function re(){
    location.reload();
}