获得当前日期n天之前的日期

版权声明： https://blog.csdn.net/qq_28256783/article/details/82147031

function getBeforeDate(n){ 
    var n = n;  
    var d = new Date();  
    var year = d.getFullYear();  
    var mon=d.getMonth()+1;  
    var day=d.getDate();  
    if(day <= n){  
        if(mon>1) {  
            mon=mon-1;  
        }else {  
            year = year-1;  
            mon = 12;  
        }  
    }  
    d.setDate(d.getDate()-n);  
    year = d.getFullYear();  
    mon=d.getMonth()+1;  
    day=d.getDate();  
    s = year+"-"+(mon<10?('0'+mon):mon)+"-"+(day<10?('0'+day):day);  
    return s;  
}