js 计算剩余 天、时、分、秒

/**
* 计算剩余 天、时、分、秒
* @param datetime long 型
* @param d
* @returns {*}
* @constructor
*/
function CountDown(datetime, d){
var now = new Date();
var leftTime = new Number(datetime) + 3600000*24*d - now.getTime();
if( leftTime > 0 ) {
var leftsecond = parseInt(leftTime/1000);
var day = Math.floor(leftsecond/(60*60*24));
var hour = Math.floor((leftsecond-day*24*60*60)/3600);
var minute = Math.floor((leftsecond-day*24*60*60-hour*3600)/60);
return {
leftTime: leftTime,
leftsecond: leftsecond,
day: day,
hour: hour,
minute: minute,
second: Math.floor(leftsecond-day*24*60*60-hour*3600-minute*60)
};
} else {
return {
leftTime : leftTime
};
}
}

/**
* 倒计时 -  显示倒计时
* @param data complaint json
* @constructor
*/
function ShowCountDownForUndo(data) {
var left = CountDown(data.longgeneratetime, 4);//距4天

if( left.leftTime > 0 ) {
$("#warnmsg").html( ( left.day*24 + left.hour) + '小时' + left.minute + ' 分 ' + left.second + ' 秒');
} else {

clearInterval(timer);
}
}

/**
* 计算剩余可输入字符，英文占半个字符
* @param f textarea
* @param maxstrlen
* @param leftCharsEl element id 显示提示信息的dom节点
*/
function calcLeftCharactors(f, maxstrlen, leftCharsDiv) {
var str = f.value;
var myLen = 0, i = 0;

for (; (i < str.length) && (myLen <= maxstrlen * 2); i++) {
if (str.charCodeAt(i) > 0 && str.charCodeAt(i) < 128)
myLen++;
else
myLen += 2;
}
if (myLen > maxstrlen * 2) {
f.value = str.substr(0, i-1);
$('#'+leftCharsDiv).html( 0 );
} else {
$('#'+leftCharsDiv).html( Math.min(maxstrlen, Math.floor((maxstrlen * 2 - myLen) / 2)) );
}
}

//计算剩余可输入字数
$('#content_').on('keyup mousedown blur paste', function(){
var me = this;
setTimeout(function(){
calcLeftCharactors(me, 100, 'content_left');
}, 100);
});