#10: i propose:
for (var i = allImgs.length; i–;)

the reason is that your shorthand method indexes the properties/items in the array before looping. My proposed method just saves the number of items in the index variable and then continues untill it reaches 0, just like with the while loops. And counting is faster than indexing.

Longhand:
if(condition){
doSomething();
}

Shorthand:
condition && doSomething();

For example:

if(document.getElementById(‘email’).value == ”){
alert(‘Please enter an e-mail address.’);
}

versus

document.getElementById(‘email’).value == ” && alert(‘Please enter an e-mail address’);