javascript实现的简易的DatePicker日历

var DatePicker = function () {
var $ = function (i) {return document.getElementById(i)},
addEvent = function (o, e, f) {o.addEventListener ? o.addEventListener(e, f, false) : o.attachEvent('on'+e, function(){f.call(o)})},
getPos = function (el) {
for (var pos = {x:0, y:0}; el; el = el.offsetParent) {
pos.x += el.offsetLeft;
pos.y += el.offsetTop;
}
return pos;
}

var init = function (n, config) {
window[n] = this;
Date.prototype._fd = function () {var d = new Date(this); d.setDate(1); return d.getDay()};
Date.prototype._fc = function () {var d1 = new Date(this), d2 = new Date(this); d1.setDate(1); d2.setDate(1); d2.setMonth(d2.getMonth()+1); return (d2-d1)/86400000;};
this.n = n;
this.config = config;
this.D = new Date;
this.el = $(config.inputId);
this.el.title = this.n+'DatePicker';

this.update();
this.bind();
}
init.prototype = {

update : function (y, m) {
var con = [], week = ['Su','Mo','Tu','We','Th','Fr','Sa'], D = this.D, _this = this;
fn = function (a, b) {return '<td title="'+_this.n+'DatePicker" class="noborder hand" onclick="'+_this.n+'.update('+a+')">'+b+'</td>'},
_html = '<table cellpadding=0 cellspacing=2>';
y && D.setYear(D.getFullYear() + y);
m && D.setMonth(D.getMonth() + m);
var year = D.getFullYear(), month = D.getMonth() + 1, date = D.getDate();
for (var i=0; i<week.length; i++) con.push('<td title="'+this.n+'DatePicker" class="noborder">'+week[i]+'</td>');
for (var i=0; i<D._fd(); i++ ) con.push('<td title="'+this.n+'DatePicker" class="noborder">&nbsp;</td>');
for (var i=0; i<D._fc(); i++ ) con.push('<td class="hand" onclick="'+this.n+'.fillInput('+year+', '+month+', '+(i+1)+')">'+(i+1)+'</td>');
var toend = con.length%7;
if (toend != 0) for (var i=0; i<7-toend; i++) con.push('<td class="noborder">&nbsp;</td>');
_html += '<tr>'+fn("-1, null", "&lt;&lt;")+fn("null, -1", "&lt;")+'<td title="'+this.n+'DatePicker" colspan=3 class="strong">'+year+'/'+month+'/'+date+'</td>'+fn("null, 1", "&gt;")+fn("1, null", "&gt;&gt;")+'</tr>';
for (var i=0; i<con.length; i++) _html += (i==0 ? '<tr>' : i%7==0 ? '</tr><tr>' : '') + con[i] + (i == con.length-1 ? '</tr>' : '');
!!this.box ? this.box.innerHTML = _html : this.createBox(_html);
},
fillInput : function (y, m, d) {
var s = this.config.seprator || '/';
this.el.value = y + s + m + s + d;
this.box.style.display = 'none';
},
show : function () {
var s = this.box.style, is = this.mask.style;
s['left'] = is['left'] = getPos(this.el).x + 'px';
s['top'] = is['top'] = getPos(this.el).y + this.el.offsetHeight + 'px';
s['display'] = is['display'] = 'block';
is['width'] = this.box.offsetWidth - 2 + 'px';
is['height'] = this.box.offsetHeight - 2 + 'px';
},
hide : function () {
this.box.style.display = 'none';
this.mask.style.display = 'none';
},
bind : function () {
var _this = this;
addEvent(document, 'click', function (e) {
e = e || window.event;
var t = e.target || e.srcElement;
if (t.title != _this.n+'DatePicker') {_this.hide()} else {_this.show()}
})
},
createBox : function (html) {
var box = this.box = document.createElement('div'), mask = this.mask = document.createElement('iframe');
box.className = this.config.className || 'datepicker';
mask.src = 'javascript:false';
mask.frameBorder = 0;
box.style.cssText = 'position:absolute;display:none;z-index:9999';
mask.style.cssText = 'position:absolute;display:none;z-index:9998';
box.title = this.n+'DatePicker';
box.innerHTML = html;
document.body.appendChild(box);
document.body.appendChild(mask);

return box;
}
}

return init;
}();

new DatePicker('_DatePicker_demo', {
inputId: 'date-input',
className: 'date-picker-wp',
seprator: '-'
});