表头固定(利用jquery实现原理介绍)

/*!
* fixHeader 1.0.0
* Copyright 2012 chokobo
*
* make table header fixed
*
* notice： set th,id border-width in IE
*
* tested browser: IE7 IE8 firefox16.0 chrome22.0
*/
(function( $, undefined ) {

$.fn.fixHeader = function(options){
var defaults = {
width: '',
height: ''

};

options = $.extend({}, defaults, options);
var elem = this;

if(options.height == ''){
return this;
}

var thead = elem.find('thead');
var fixTable = elem.clone().empty().removeAttr('id');
//set head default background-color
if(fixTable.css('background-color') == 'transparent' || fixTable.css('background-color') == ''){
fixTable.css('background-color', '#fff');
}
fixTable.css({
'position': 'absolute',
'top': '0px',
'border-bottom': $('tr:eq(0)', thead).find('th:eq(0), td:eq(0)').css('border-bottom-width')
});


$('tr:eq(0)', thead).find('th, td').each(function(){
var col = $(this);

if($.browser.mozilla){
col.width(col.width());
}
else if($.browser.chrome){
var colBorderWidth = parseInt(col.css('border-width'));
col.width(col.width()+colBorderWidth);
}
else if($.browser.msie){
var colBorderWidth = parseInt(col.css('border-width'));
if(colBorderWidth){
col.width(col.width()+colBorderWidth+colBorderWidth/2);//IE7??
}
}
});

//make head
var dummyHead = thead.clone();
thead.appendTo(fixTable);
dummyHead.prependTo(elem);


var tbodyWrapper = elem.wrap('<div class="body-wrapper"></div>').parent();
var tableWrapper = tbodyWrapper.wrap('<div class="table-wrapper" style="position:relative;"/>').parent();
setTableWidth();
setWrapperSize();

fixTable.prependTo(tableWrapper);

return this;

function setTableWidth(){
if($.browser.mozilla){
elem.width(elem.width());
fixTable.css('width',elem.css('width'));
}
else if($.browser.chrome){
elem.width(elem.outerWidth());
fixTable.width(elem.outerWidth());
}
else if($.browser.msie){
elem.width(elem.outerWidth());
fixTable.width(elem.outerWidth());
}
else{
elem.width(elem.outerWidth());
fixTable.width(elem.outerWidth());
}
}
function setWrapperSize(){
var elemWidth = elem.outerWidth(true);
var elemHeight = elem.outerHeight(true);
var scrollBarWidth = 20;

if(options.width == ''){
tbodyWrapper.css({
'width': (elemWidth+scrollBarWidth) + 'px',
'height': options.height,
'overflow-x': 'hidden',
'overflow-y': 'auto'
});
}
else{
if(elemWidth <= options.width){
tbodyWrapper.css({
'width': options.width+'px',
'height': options.height,
'overflow-x': 'hidden',
'overflow-y': 'auto'
});
}
else{
tableWrapper.css({
'width': options.width,
'height': options.height,
'overflow': 'auto'
});
tableWrapper.scroll(function(){
fixTable.css('top',tableWrapper.scrollTop()+'px');
});
}
}
}
};

})( jQuery );

/*
功能：固定表頭。
使用容器的ID進行設定$("#div").chromatable({width: "100%",height: "100%", scrolling: "yes"})
table必須包含有<thead>標籤
參數：無。
*/
(function($){
$.chromatable = {
defaults: {
width: "900px", //設定容器寬度,待擴展程式
height: "300px", //設定容器高度,待擴展程式
scrolling: "yes" //yes跟隨IE滾動條而滑動, no固定在頁面上僅容器滾動條滑動
}
};
$.fn.chromatable = function(options){
var options = $.extend({}, $.chromatable.defaults, options);
return this.each(function(){
var $divObj = $(this);
var $tableObj = $divObj.find("table");
var $uniqueID = $tableObj.attr("ID") + ("wrapper");
var $class = $tableObj.attr("class");
var $tableWidth = $tableObj.width();
var top = $("#"+$tableObj.attr("ID")).offset().top;
var left = $("#"+$tableObj.attr("ID")).offset().left
$divObj.append("<table class='"+$class+"' id='"+$uniqueID+"' style='position:absolute;top:" +top+"px;left:"+left+"px;' width='"+$tableWidth+"' border='0' cellspacing='0' cellpadding='0'><thead>"+$("#"+$tableObj.attr("ID")).find("thead").html()+"</thead></table>");

$.each($("#"+$tableObj.attr("ID")).find("thead th"), function(i,item){
$("#"+$uniqueID).find("thead th").eq(i).width($(item).width());
$(item).width($(item).width());
});

if(options.scrolling === "yes")
{
scrollEvent($tableObj.attr("ID"), $uniqueID);
}
resizeEvent($tableObj.attr("ID"), $uniqueID);
});

function scrollEvent(tableId, uniqueID)
{
var element = $("#"+uniqueID);
$(window).scroll(function(){
var top = $("#"+tableId).offset().top;
var scrolls = $(this).scrollTop();

if (scrolls > top) {
if (window.XMLHttpRequest) {
element.css({
position: "fixed",
top: 0
});
} else {
element.css({
top: scrolls
});
}
}else {
element.css({
position: "absolute",
top: top
});
}

});
};

function resizeEvent(tableId, uniqueID)
{
var element = $("#"+uniqueID);
$(window).resize(function(){
var top = $("#"+tableId).offset().top;
var scrolls = $(this).scrollTop();
if (scrolls > top) {
if (window.XMLHttpRequest) {
element.css({
position: "fixed",
top: 0
});
} else {
element.css({
top: scrolls
});
}
}else {
element.css({
position: "absolute",
top: top
});
}
});
}
};
})(jQuery);