js获取当前时间前后N天前后日期的方法

function  GetDateStr(AddDayCount) { 
    var  dd =  new  Date();
    dd.setDate(dd.getDate()+AddDayCount); //获取AddDayCount天后的日期
    var  y = dd.getFullYear(); 
    var  m = (dd.getMonth()+1)<10? "0" +(dd.getMonth()+1):(dd.getMonth()+1); //获取当前月份的日期，不足10补0
    var  d = dd.getDate()<10? "0" +dd.getDate():dd.getDate(); //获取当前几号，不足10补0
    return  y+ "-" +m+ "-" +d; 
}
 
 
console.log( "半年前：" +GetDateStr(-180));
console.log( "三月前：" +GetDateStr(-90));
console.log( "一月前：" +GetDateStr(-30));
console.log( "昨天：" +GetDateStr(-1));
console.log( "今天：" +GetDateStr(0));