/*
* file everywhere - 瀏覽器通用文件上傳
* copyright->flowerszhong
* flowerszhong@gmail.com
* http://www.cnblogs.com/flowerszhong/
*/
(function($) {
$.fn.fileEveryWhere = function(options) {
var defaults = {
WrapWidth: 300,
WrapHeight: 30,
ButtonWidth: 60,
ButtonHeight: 28,
ButtonText: "瀏覽",
TextHeight: 28,
TextWidth: 240
};
var options = $.extend(defaults, options);
var browser_ver = $.browser.version.substr(0, 1);
var displayMode = ($.browser.msie && browser_ver <= "7") ? "inline" : "inline-block";
return this.each(function() {
//創(chuàng)建包含，設(shè)置為相對定位
var wrapper = $("<div class='fileWraper'>")
.css({
"width": options.WrapWidth + "px",
"height": options.WrapHeight + "px",
"display": displayMode,
"zoom": "1",
"position": "relative",
"overflow": "hidden",
"z-index":"1"
});
//創(chuàng)建文本輸入框，用于存放上傳文件名稱
var text = $('<input class="filename" type="text" />')
.css({
"width": options.TextWidth + "px",
"heigth": options.TextHeight + "px"
});
//創(chuàng)建瀏覽按鈕
var button = $('<input class="btnfile" type="button" />')
.val(options.ButtonText);
$(this).wrap(wrapper).parent().append(text, button);
$(this).css({
"position": "absolute",
"top": "0",
"left": "0",
"z-index": "2",
"height": options.WrapHeight + "px",
"width": options.WrapWidth + "px",
"cursor": "pointer",
"opacity": "0.0",
"outline":"0",
"filter": "alpha(opacity:0)"
});
if ($.browser.mozilla) { $(this).attr("size", 1 + (options.WrapWidth - 85) / 6.5) }
$(this).bind("change", function() {
text.val($(this).val());
});
});
};
})(jQuery);

<script type="text/javascript">
$(function() {
var fileArray = [];
var i = 0;
while (i < 100) {
fileArray.push(i + ":<input type='file' size='" + i + "' /><br />");
i++;
}
document.write(fileArray.join(""));
$("input:file").each(function() { $(this).after("<b>" + $(this).width() + "</b>") });
});
</script>

if ($.browser.mozilla) { $(this).attr("size", 1 + (options.WrapWidth - 85) / 6.5)