最大延时上限

关于setTimeout的最大延时上限
http://www.cnblogs.com/meteoric_cry/archive/2011/04/01/2002240.html

if (duration > 24*60*60*1000) {
    duration = 24*60*60*1000;
}
返回ID值的 
<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="utf-8" />
    <title></title>
</head>
<body>
    <div id="box1">box1</div>
    <div id="box2">box2</div>
    <script>
        var timer;
        var i = 1;
        function auto() {
            timer = setInterval(function() {
                console.log(i);
                if (++i > 4) {
                    i = 1;
                }
            }, 1000);
        }
        auto();
        console.log(timer); // 1 不是setInterval(function...
        document.getElementById('box1').onclick = function() {
            clearInterval(timer);
        }
        document.getElementById('box2').onclick = function() {
            auto();
        }
    </script>
</body>
</html>
setTimeout延时0毫秒

setTimeout延时0毫秒的作用
http://www.cnblogs.com/xieex/archive/2008/07/11/1241137.html

<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="utf-8" />
    <title></title>
</head>
<body>
    <input id="t1" type="text" onkeydown="document.getElementById('t1text').innerHTML=this.value;" />
    <span id="t1text"></span> 
    <input id="t2" type="text" onkeydown="var t2=this;setTimeout(function(){document.getElementById('t2text').innerHTML=t2.value},0);" />
    <span id="t2text"></span> 

    <input id="makeinput" type="button" value="生成input" />
    <span id="inpwrapper"></span>
    <input id="makeinput2" type="button" value="生成input" />
    <span id="inpwrapper2"></span>

    <script>
        // 1 3 2
        console.log(1);
        setTimeout(function() {console.log(2)}, 0);
        console.log(3);

        function get(id) {
            return document.getElementById(id);
        }
        get('makeinput').onmousedown = function() {
            var input = document.createElement('input');
            input.setAttribute('type', 'text');
            input.setAttribute('value', 'test1');
            get('inpwrapper').appendChild(input);
            input.focus();
            input.select();
        };
        get('makeinput2').onmousedown = function() {
            var input = document.createElement('input');
            input.setAttribute('type', 'text');
            input.setAttribute('value', 'test1');
            get('inpwrapper2').appendChild(input);
            setTimeout(function(){
                input.focus();
                input.select();
            }, 0);
        };
    </script>
</body>
</html>