基础知识,抄袭只会知其然而不知其所以然.
Date.prototype.isleap = function () {
var y = this.getFullYear();
return (((y) % 4) == 0 && (((y) % 100) != 0 || ((y) % 400) == 0))
};
Date.prototype.addDay = function (day) {
this.setTime(this.getTime() + (day * 24 * 3600 * 1000));
};
Date.prototype.addMonth = function (month) {
var day = 0;
var daymilliseconds = 86400000;
var count = Math.abs(month);
for (var i = 0 ; i < count ; ++i) {
var mon = this.getMonth() + 1;
if (mon == 4 || mon == 6 || mon == 9 || mon == 11) {
day = 30
} else if (mon == 2) {
day = this.isleap() ? 29 : 28;
} else {
day = 31;
}
var milliseconds = day * daymilliseconds;
milliseconds = (month >= 0 ? milliseconds : 0 - milliseconds);
this.setTime(this.getTime() + milliseconds);
}
};