Increasing opacity based on an element's location

I've got a piece of code that takes an element, checks where it is, and if it's beyond a set place in the viewport, make the opacity increase to 1. I've made the code so that it only runs the checks if they're needed, the problem is that the code looks atrocious, and I suspect there's a better way for me to be doing it.

```
var $wheresThisAt = viewportHeight*4;
if (scrolled > ($wheresThisAt))
{
//there has to bve a better way...
$('.salafoot').css('opacity', '0');
$('#salamander-1').css('opacity', '1');
if (scrolled > (($wheresThisAt)+20)){
$('#salamander-2').css('opacity', '1');
if (scrolled > (($wheresThisAt)+40)){
$('#salamander-3').css('opacity', '1');
if (scrolled > (($wheresThisAt)+60)){
$('#salamander-4').css('opacity', '1');
if (scrolled > (($wheresThisAt)+80)){
$('#salamander-5').css('opacity', '1');
if (scrolled > (($wheresThisAt)+100)){
$('#salamander-6').css('opacity', '1');
if (scrolled > (($wheresThisAt)+120)){
$('#salamander-7').css('opacity', '1');
if (scrolled > (($wheresThisAt)+140)){
$('#salamander-8').css('opacity', '1');
if (scrolled > (($wheresThisAt)+160)){
$('#salamander-9').css('opacity', '1');
if (scrolled > (($wheresThisAt)+180)){
$('#salamander-10').css('opacity', '1');
if (scrolled > (($wheresThisAt)+200)){
$('#salamander-11').css('opacity', '1');
if (scrolled > (($wheresThisAt)+220)){
$('#salamander-12').css('opacity', '1');
if (scrolled > (($wheresThisAt)+240)){
$('#salamander-13').css('opacity', '1');
if (scrolled > (($wheresThisAt)+260)){
$('#salamander-14').css('opacity', '1');
if (scrolled > (($wheresThisAt)+2

Gah! Thanks for coming here.

Essentially, all your if-statements have the following structure:

if (scrolled > (($wheresThisAt)+(N * 20))){
    $('#salamander-(N + 1)').css('opacity', '1');

So we can comfortably roll that into a loop:

for (var i = 0; i < 35; i++) {
    if (scrolled <= ($wheresThisAt + i * 20)) {
        break;
    }
    $("#salamander-" + (i + 1)).css('opacity', '1');
}

StackExchange Code Review Q#45596, answer score: 17