setInterval,setTimeout,clearInterval

setInterval（fun,time)函数fun以间隔time循环执行

clearInterval（timer）清除定时器

setTimeout（fun，time)函数fun在time后执行一次

下面实现一个图片滚动效果：

function Get(obj) {
    return document.getElementById(obj);
}

function Marquee() {
    var Slider = Get("Slider");
    totalScollWidth = GetScrollWidth(scrollNum);
    var moveLength = totalScollWidth + 25 +ImgSpace;
    for (var i = 0; i < moveLength; i++) {
        Slider.scrollLeft += 1;
    }
    ImgSpace = 0;
    clearInterval(timer);
    scrollNum++;
    var timeout = setTimeout(Stop, 3000); //停3秒
    
    if (scrollNum > GetScrollNum()) {
        Slider.scrollLeft = 0;
        scrollNum = 0;
    }
}

function Start() {
    timer = setInterval(Marquee, speed);
}

function Stop()
{
    timer = setInterval(Marquee, speed);
}