The usage of timer setTimeout in javascript is generally as follows. After calling beginrotate, it enters a process of timing execution of rotateloop, as follows:

var angle = 0;

function rotateloop() {
if (angle < 360) {
angle++;
//use angle
//......
setTimeout("rotateloop()", 100);
}
}

function beginrotate() {
//do something
//......
setTimeout("rotateloop()", 100);
}

This code has a problem, is produced a global variable Angle, which is obviously not a good programming habit, so we thought of using the way of embedded function, the code as follows:

function beginrotate() {

var angle = 0;

function rotateloop() {
if (angle < 360) {
angle++;
//use angle
//......
setTimeout("rotateloop()", 100);
}
}
//do something
//......
setTimeout("rotateloop()", 100);
}

After this is changed, found javascript error, rotateloop can not find, obviously setTimeout did not find the rotateloop this local nested function, here as long as a little change can solve the problem, the code is as follows:

function beginrotate() {

var angle = 0;

function rotateloop() {
if (angle < 360) {
angle++;
//use angle
//......
setTimeout(rotateloop, 100);
}
}
//do something
//......
setTimeout(rotateloop, 100);
}

All you need to do is change the first argument of setTimeout to a function object, not a string.