javascript - new Date() 返回未定义

Question

我有这个代码:

function submit(){
//Some stuff here...

clicked= false

//Some stuff here...

function start() {
    var starttime;
    if(clicked===false)
    {
        document.getElementById("start").innerHTML = "Submit";
        starttime = new Date();
        document.getElementById("title").innerHTML = "<b>...</b>";
        clicked=true;
    } else {
        var endtime = new Date();
        var timediff = endtime - starttime;
        alert(typeof endtime + typeof starttime + typeof timediff + timediff + endtime + starttime);
        submit();
    }
}

timediff 始终返回 NaN。当我使用 typeof 时，starttime 未定义，endtime 是一个对象，timediff 是一个数字。为什么？有解决办法吗？谢谢

Answer 1

您需要将启动时间设置为全局才能使其工作:

clicked= false;
var starttime;

//Some stuff here...

function start() {

    if(clicked === false) {
        document.getElementById("start").innerHTML = "Submit";
        starttime = new Date();
        document.getElementById("title").innerHTML = "<b>...</b>";
        clicked=true;
    } else {
        var endtime = new Date();
        var timediff = endtime - starttime;
        alert(typeof endtime + typeof starttime + typeof timediff + timediff + endtime + starttime);
        submit();
    }
}