当前的组合框实现方式是每次展开下拉列表时都会清空并重新渲染完整列表。此外，您必须将minLength设置为0，因为它需要执行空搜索来获取完整列表。
以下是我自己扩展自动完成小部件的实现。在我的测试中，即使在IE 7和8上，它也可以轻松处理5000个项目的列表。它只会渲染完整列表一次，并在每次单击下拉按钮时重用它。这也消除了选项minLength = 0的依赖性。它还适用于数组和ajax作为列表源。此外，如果您有多个大型列表，则将小部件初始化添加到队列中，以便可以在后台运行而不会冻结浏览器。
<script>
(function($){
$.widget( "ui.combobox", $.ui.autocomplete,
{
options: {
minLength: 2,
ajaxGetAll: {get: "all"}
},
_create: function(){
if (this.element.is("SELECT")){
this._selectInit();
return;
}
$.ui.autocomplete.prototype._create.call(this);
var input = this.element;
input.addClass( "ui-widget ui-widget-content ui-corner-left" );
this.button = $( "<button type='button'> </button>" )
.attr( "tabIndex", -1 )
.attr( "title", "Show All Items" )
.insertAfter( input )
.button({
icons: { primary: "ui-icon-triangle-1-s" },
text: false
})
.removeClass( "ui-corner-all" )
.addClass( "ui-corner-right ui-button-icon" )
.click(function(event) {
if ( input.combobox( "widget" ).is( ":visible" ) ) {
input.combobox( "close" );
return;
}
var data = input.data("combobox");
clearTimeout( data.closing );
if (!input.isFullMenu){
data._swapMenu();
input.isFullMenu = true;
}
input.combobox( "widget" ).css( "display", "block" )
.position($.extend({ of: input },
data.options.position
));
input.focus();
data._trigger( "open" );
});
$(document).queue(function(){
var data = input.data("combobox");
if ($.isArray(data.options.source)){
$.ui.combobox.prototype._renderFullMenu.call(data, data.options.source);
}else if (typeof data.options.source === "string") {
$.getJSON(data.options.source, data.options.ajaxGetAll , function(source){
$.ui.combobox.prototype._renderFullMenu.call(data, source);
});
}else {
$.ui.combobox.prototype._renderFullMenu.call(data, data.source());
}
});
},
_renderFullMenu: function(source){
var self = this,
input = this.element,
ul = input.data( "combobox" ).menu.element,
lis = [];
source = this._normalize(source);
input.data( "combobox" ).menuAll = input.data( "combobox" ).menu.element.clone(true).appendTo("body");
for(var i=0; i<source.length; i++){
lis[i] = "<li class=\"ui-menu-item\" role=\"menuitem\"><a class=\"ui-corner-all\" tabindex=\"-1\">"+source[i].label+"</a></li>";
}
ul.append(lis.join(""));
this._resizeMenu();
setTimeout(function(){
self._setupMenuItem.call(self, ul.children("li"), source );
}, 0);
input.isFullMenu = true;
},
_setupMenuItem: function( items, source ){
var self = this,
itemsChunk = items.splice(0, 500),
sourceChunk = source.splice(0, 500);
for(var i=0; i<itemsChunk.length; i++){
$(itemsChunk[i])
.data( "item.autocomplete", sourceChunk[i])
.mouseenter(function( event ) {
self.menu.activate( event, $(this));
})
.mouseleave(function() {
self.menu.deactivate();
});
}
if (items.length > 0){
setTimeout(function(){
self._setupMenuItem.call(self, items, source );
}, 0);
}else {
$(document).dequeue();
}
},
_renderItem: function( ul, item ) {
var label = item.label.replace( new RegExp(
"(?![^&;]+;)(?!<[^<>]*)(" + $.ui.autocomplete.escapeRegex(this.term) +
")(?![^<>]*>)(?![^&;]+;)", "gi"), "<strong>$1</strong>" );
return $( "<li></li>" )
.data( "item.autocomplete", item )
.append( "<a>" + label + "</a>" )
.appendTo( ul );
},
destroy: function() {
if (this.element.is("SELECT")){
this.input.remove();
this.element.removeData().show();
return;
}
$.ui.autocomplete.prototype.destroy.call(this);
this.element.removeClass( "ui-widget ui-widget-content ui-corner-left" );
this.button.remove();
},
search: function( value, event){
var input = this.element;
if (input.isFullMenu){
this._swapMenu();
input.isFullMenu = false;
}
$.ui.autocomplete.prototype.search.call(this, value, event);
},
_change: function( event ){
abc = this;
if ( !this.selectedItem ) {
var matcher = new RegExp( "^" + $.ui.autocomplete.escapeRegex( this.element.val() ) + "$", "i" ),
match = $.grep( this.options.source, function(value) {
return matcher.test( value.label );
});
if (match.length){
match[0].option.selected = true;
}else {
this.element.val( "" );
if (this.options.selectElement) {
this.options.selectElement.val( "" );
}
}
}
$.ui.autocomplete.prototype._change.call(this, event);
},
_swapMenu: function(){
var input = this.element,
data = input.data("combobox"),
tmp = data.menuAll;
data.menuAll = data.menu.element.hide();
data.menu.element = tmp;
},
_selectInit: function(){
var select = this.element.hide(),
selected = select.children( ":selected" ),
value = selected.val() ? selected.text() : "";
this.options.source = select.children( "option[value!='']" ).map(function() {
return { label: $.trim(this.text), option: this };
}).toArray();
var userSelectCallback = this.options.select;
var userSelectedCallback = this.options.selected;
this.options.select = function(event, ui){
ui.item.option.selected = true;
if (userSelectCallback) userSelectCallback(event, ui);
if (userSelectedCallback) userSelectedCallback(event, ui);
};
this.options.selectElement = select;
this.input = $( "<input>" ).insertAfter( select )
.val( value ).combobox(this.options);
}
}
);
})(jQuery);
</script>
