for (var i = 0, j = doSomething(); i < length; i++) {
    doSomething();
}
for (; i < length; i++) {
    doSomething();
}
for (; i < length;) {
    doSomething();
}
for (var i = 0;; i++) {
    doSomething();
}
for (;;) {
    doSomething();
}
for (var key in document) {
    doSomething();
}
