日期提前一周功能

var oldFormatDate = function (date) {
        var y = date.getFullYear();
        var m = date.getMonth() + 1;
        m = m < 10 ? '0' + m : m;
        var d = date.getDate()-7;
        d = d < 10 ? ('0' + d) : d;
        return y + '-' + m + '-' + d;
    };
    var formatDate = function (date) {
        var y = date.getFullYear();
        var m = date.getMonth() + 1;
        m = m < 10 ? '0' + m : m;
        var d = date.getDate();
        d = d < 10 ? ('0' + d) : d;
        return y + '-' + m + '-' + d;
    };
      var date = new Date();
      var oldTransDate = oldFormatDate(date);
      var newTransDate = formatDate(date);
      var transDate = oldTransDate +" ~ "+newTransDate;