JavaScript如何获得某一天的前一天日期
网上看到一段代码，可以获得系统当前日期的前一天。
如何获得任意选定一天的前一天呢？
不要说直接减1啊。例如：20120301减1就为20120300了，应该是20120229
系统当前日期的前一天代码：

JScript code

    function GetDay()       {           var today=new Date();        var yesterday_milliseconds=today.getTime()-1000*60*60*24;                var yesterday=new Date();              yesterday.setTime(yesterday_milliseconds);                         var strYear=yesterday.getFullYear();           var strDay=yesterday.getDate();           var strMonth=yesterday.getMonth()+1;           if(strMonth<10)           {               strMonth="0"+strMonth;           }           var strYesterday=strYear+"-"+strMonth+"-"+strDay;           alert(strYesterday);    }

如何获得任意一天的前一天呢？

[解决办法]
var d = new Date(2012, 0, 1);
d.setTime(d.getTime()-24*60*60*1000);

[解决办法]
new Date(d.getFullYear(),d.getMonth(),d.getDate()-1)
[解决办法]

探讨

[解决办法]

JScript code

s = "20120301";alert(getPreDay(s));function getPreDay(s){    var y = parseInt(s.substr(0,4), 10);    var m = parseInt(s.substr(4,2), 10)-1;    var d = parseInt(s.substr(6,2), 10);    var dt = new Date(y, m, d-1);    y = dt.getFullYear();    m = dt.getMonth()+1;    d = dt.getDate();    m = m<10?m:"0"+m;    d = d<10?d:"0"+d;    return y + "" + m + "" + d;}
[解决办法]
正解
探讨


new Date(d.getFullYear(),d.getMonth(),d.getDate()-1)

[解决办法]
探讨


JScript code


s = "20120301";
alert(getPreDay(s));

function getPreDay(s){
    var y = parseInt(s.substr(0,4), 10);
    var m = parseInt(s.substr(4,2), 10)-1;
    var d = parseInt(s.substr(6,2), 10……

[解决办法]
探讨

JScript code


s = "20120301";
alert(getPreDay(s));

function getPreDay(s){
    var y = parseInt(s.substr(0,4), 10);
    var m = parseInt(s.substr(4,2), 10)-1;
    var d = parseInt(s.substr(6……

[解决办法]
用你这个简单改一下就可以
JScript code
function GetDay(year, month, day)       {           var today=new Date(year, month-1 ,day);        var yesterday_milliseconds=today.getTime()-1000*60*60*24;                var yesterday=new Date();              yesterday.setTime(yesterday_milliseconds);                         var strYear=yesterday.getFullYear();           var strDay=yesterday.getDate();           var strMonth=yesterday.getMonth()+1;           if(strMonth<10)           {               strMonth="0"+strMonth;           }           var strYesterday=strYear+"-"+strMonth+"-"+strDay;           alert(strYesterday);    }    GetDay(2012, 1, 5);