JavaScript - for iteration advanced tips and examples

for-iteration-strategies.js

for (var i=0, each; each = arr[i]; i++) {
    doSomething(each);
}

for (var i=arr.length; i--;) {
    var member = arr[i];
    doSomething(member);
}

function sum(arr) {
    for (var i=arr.length, r=0; i--; r += arr[i]);
    return r;
}
sum([3,5,0,-2,7,8]); //21\

function shoutOutSum(arr, x) {
    for (var i=arr.length, r=0; i-- || alert(r); r += arr[i]);
}
shoutOutSum([3,5,0,-2,7,8]); //alerts "21"

var i = 0;
for (
    console.log('start:',+new Date); 
    i<1000 || console.log('finish:',+new Date); 
    i++
);