利用JQuery为搜索栏增加tag提示

很简单的一个功能，就是当用户在搜索栏输入搜索字符时候，利用JQuery的功能把一些预设好的关键字浮现出来，除了让用户意外一下，还有就是让用户简化输入。比如象下图的样子：

实现的方法很简单，首先是要在你的网站上加载JQuery，然后再加载下面的JS文件，下载之

(function($){var globalTags=[];window.setGlobalTags=function(tags){globalTags=getTags(tags);};function getTags(tags){var tag,i,goodTags=[];for(i=0;i<tags.length;i++){tag=tags[i];if(typeof tags[i]=='object'){tag=tags[i].tag;} 
goodTags.push(tag.toLowerCase());} 
return goodTags;} 
$.fn.tagSuggest=function(options){var defaults={'matchClass':'tagMatches','tagContainer':'span','tagWrap':'span','sort':true,'tags':null,'url':null,'delay':0,'separator':' '};var i,tag,userTags=[],settings=$.extend({},defaults,options);if(settings.tags){userTags=getTags(settings.tags);}else{userTags=globalTags;} 
return this.each(function(){var tagsElm=$(this);var elm=this;var matches,fromTab=false;var suggestionsShow=false;var workingTags=[];var currentTag={"position":0,tag:""};var tagMatches=document.createElement(settings.tagContainer);function showSuggestionsDelayed(el,key){if(settings.delay){if(elm.timer)clearTimeout(elm.timer);elm.timer=setTimeout(function(){showSuggestions(el,key);},settings.delay);}else{showSuggestions(el,key);}} 
function showSuggestions(el,key){workingTags=el.value.split(settings.separator);matches=[];var i,html='',chosenTags={},tagSelected=false;currentTag={position:currentTags.length-1,tag:''};for(i=0;i<currentTags.length&&i<workingTags.length;i++){if(!tagSelected&¤tTags[i].toLowerCase()!=workingTags[i].toLowerCase()){currentTag={position:i,tag:workingTags[i].toLowerCase()};tagSelected=true;} 
chosenTags[currentTags[i].toLowerCase()]=true;} 
if(currentTag.tag){if(settings.url){$.ajax({'url':settings.url,'dataType':'json','data':{'tag':currentTag.tag},'async':false,'success':function(m){matches=m;}});}else{for(i=0;i<userTags.length;i++){if(userTags[i].indexOf(currentTag.tag)===0){matches.push(userTags[i]);}}} 
matches=$.grep(matches,function(v,i){return!chosenTags[v.toLowerCase()];});if(settings.sort){matches=matches.sort();} 
for(i=0;i<matches.length;i++){html+='<'+settings.tagWrap+' class="_tag_suggestion">'+matches[i]+'</'+settings.tagWrap+'>';} 
tagMatches.html(html);suggestionsShow=!!(matches.length);}else{hideSuggestions();}} 
function hideSuggestions(){tagMatches.empty();matches=[];suggestionsShow=false;} 
function setSelection(){var v=tagsElm.val();if(v==tagsElm.attr('title')&&tagsElm.is('.hint'))v='';currentTags=v.split(settings.separator);hideSuggestions();} 
function chooseTag(tag){var i,index;for(i=0;i<currentTags.length;i++){if(currentTags[i].toLowerCase()!=workingTags[i].toLowerCase()){index=i;break;}} 
if(index==workingTags.length-1)tag=tag+settings.separator;workingTags[i]=tag;tagsElm.val(workingTags.join(settings.separator));tagsElm.blur().focus();setSelection();} 
function handleKeys(ev){fromTab=false;var type=ev.type;var resetSelection=false;switch(ev.keyCode){case 37:case 38:case 39:case 40:{hideSuggestions();return true;} 
case 224:case 17:case 16:case 18:{return true;} 
case 8:{if(this.value==''){hideSuggestions();setSelection();return true;}else{type='keyup';resetSelection=true;showSuggestionsDelayed(this);} 
break;} 
case 9:case 13:{if(suggestionsShow){chooseTag(matches[0]);fromTab=true;return false;}else{return true;}} 
case 27:{hideSuggestions();setSelection();return true;} 
case 32:{setSelection();return true;}} 
if(type=='keyup'){switch(ev.charCode){case 9:case 13:{return true;}} 
if(resetSelection){setSelection();} 
showSuggestionsDelayed(this,ev.charCode);}} 
tagsElm.after(tagMatches).keypress(handleKeys).keyup(handleKeys).blur(function(){if(fromTab==true||suggestionsShow){fromTab=false;tagsElm.focus();}});tagMatches=$(tagMatches).click(function(ev){if(ev.target.nodeName==settings.tagWrap.toUpperCase()&&$(ev.target).is('._tag_suggestion')){chooseTag(ev.target.innerHTML);}}).addClass(settings.matchClass);setSelection();});};})(jQuery);

接着就是编辑你自己的关键字。这里的做法是你自己自行编辑，还有很多方法是直接查询WordPress的数据库的。但那样做就显得很专业的样子。对于我自己来说，本来站内的搜索功能就不是很受用，为了那没多被使用过几次的搜索而复杂这个提示功能显然不值，所以还是自己来编辑一些重要的关键字好了。下面的代码也要整合到网站的JS文件中：

<script type="text/javascript"> 
$(document).ready(function() { 
$('#tags').tagSuggest({ 
tags: ["WordPress","WordPress 主题","WordPress 插件","生活","巴黎","设计","法国","照片","朋友","技巧","下载","JQuery","JQuery 教程","JQuery 例子","twitter","Google","seo","firefox","firefox 扩展","css","ajax","theme","theme 教程","theme 技巧","Js-O3","Js-Paper","blackberry","blackberry 8900"] 
}); 
}); 
</script>

能看出上面的关键字编辑了吧。
然后最后一步就是需要指定相应的搜索栏，如上面代码中的"#tags"就是决定这个东西。修改搜索栏的ID，让其适应则可。也就是说为搜索栏的input内添加一个id="tags"则可。或者你也可以修改上面的代码内的ID，让其适应你原有的搜索栏内input的ID。
当然还有对关键字的样式设定，这个就随大家爱好了，我这里不列出。
tag.js 打包下载