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"> </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"> </td>'); 
_html += '<tr>'+fn("-1, null", "<<")+fn("null, -1", "<")+'<td title="'+this.n+'DatePicker" colspan=3 class="strong">'+year+'/'+month+'/'+date+'</td>'+fn("null, 1", ">")+fn("1, null", ">>")+'</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: '-' 
});