js input框自动补全

效果：
css：

div,p,h1,h2,h3,h4,h5,h6,ul,li,span,input{
    box-sizing: border-box;
    font: 14px/20px "microsoft yahei";
}
div.wrap{
    width: 240px;
    margin: 20px auto 0 auto;
}
.auto-inp{
    width: 240px;
    height: 36px;
    padding-left: .5em;
    border-radius: 2px;
    border: 1px solid #dedede;
    color: #666;
    outline: none;
}
.auto{
    width: 240px;
    border: 1px solid #dedede;
    border-top: none;
    position: absolute;
}
.auto_out{
    width: 238px;
    height: 36px;
    line-height: 36px;
    padding-left: .5em;
    color: #000;
    background: #fff;
    overflow: hidden;
    white-space: nowrap;
    -o-text-overflow: ellipsis;
    text-overflow: ellipsis;
}
.auto_out.on{
    background: #eee;
    cursor: pointer;
}
.hidden{
    display: none;
}

html：

<div class="wrap">
    <input type="text" id="input" class="auto-inp">
    <div class="auto hidden" id="auto">
        <div class="auto_out">1div>
        <div class="auto_out">2div>
    div>
div>

<script src="auto.js">script>
<script>
    var array = ['七里香','b0','b12','b22','b3','b4','b5','b6','如果爱','b7','b8','b2','abd','ab','acd','accd','abd','qq音乐','b1','cd','ccd','cbcv','小王子','cxf','b0'];
    var autoComplete = new AutoComplete("input","auto",array);
    document.getElementById("input").onkeyup = function(event){
        autoComplete.start(event);
    }
script>

auto.js：

// 数组去重
Array.prototype.unique = function(){
    this.sort();
    var res = [];
    var json = {};
    for (var i = 0; i < this.length; i++) {
        if(!json[this[i]]){
            res.push(this[i]);
            json[this[i]] = 1;
        }
    }
    return res;
}

// 对样式操作
var setClass = {
    hasClass: function(elements,cName){ // 判断是否含有某个class
        if(elements.className.match(new RegExp( "(\\s|^)" + cName + "(\\s|$)") ))
            return true;
        else
            return false;
    },
    addClass: function(elements,cName){ // 添加class
        if( !this.hasClass( elements,cName ) ){ 
            elements.className += " " + cName; 
        };
    },
    removeClass: function(elements,cName){  // 移除某个class
        if( this.hasClass( elements,cName ) ){ 
            elements.className = elements.className.replace( new RegExp( "(\\s|^)" + cName + "(\\s|$)" )," " ); 
        }
    }
}

var Bind = function(This){
    return function(){
        This.init();
    }
}

function AutoComplete(input,auto,arr) {
    this.obj = document.getElementById(input);
    this.autoObj = document.getElementById(auto);
    this.search_value = ""; //当前的搜索输入值
    this.index = -1;        //当前选中的DIV的索引
    this.value_arr = arr;   //数据库中供检索的值 不包含重复值
}
AutoComplete.prototype = {
    // 初始化
    init: function(){
        var This = this;
        setClass.removeClass(This.autoObj,"hidden");
        this.autoObj.style.left = this.obj.offsetLeft + "px";
        this.autoObj.style.top = this.obj.offsetTop + this.obj.offsetHeight + "px";
    },
    //删除自动完成需要的所有DIV
    deleteDIV: function(){
        while(this.autoObj.hasChildNodes()){
            this.autoObj.removeChild(this.autoObj.firstChild);
        }
        setClass.addClass(this.autoObj,"hidden");
    },
    autoOnmouseover: function(index){
        if(index != this.index){
            setClass.addClass(this.autoObj.children[index],"on");
            setClass.removeClass(this.autoObj.children[this.index],"on");
            this.index = index;
        }
    },
    setValue: function(This){
        return function(){
            This.obj.value = this.seq;
            setClass.addClass(This.autoObj,"hidden");
        }
    },
    // 响应键盘
    pressKey: function(event){
        var code = event.keyCode;
        var length = this.autoObj.children.length;
        if(code == 38){     //↑
            setClass.removeClass(this.autoObj.children[this.index],"on");
            this.index--;
            if(this.index < 0){
                this.index = length - 1;
            }
            setClass.addClass(this.autoObj.children[this.index],"on");
            this.obj.value = this.autoObj.children[this.index].seq;
        }else if(code == 40){   //↓
            setClass.removeClass(this.autoObj.children[this.index],"on");
            this.index++;
            if(this.index > length-1){
                this.index = 0;
            }
            setClass.addClass(this.autoObj.children[this.index],"on");
            this.obj.value = this.autoObj.children[this.index].seq;
        }else{          //回车
            this.obj.value = this.autoObj.children[this.index].seq;
            setClass.addClass(this.autoObj,"hidden");
            this.index = -1;
        }
    },
    // 程序入口
    start: function(event){
        event = event || window.event;
        var code = event.keyCode;
        var This = this;
        if(code != 13 && code != 38 && code != 40){
            this.init();
            this.deleteDIV();
            this.search_value = this.obj.value;
            var valueArr = this.value_arr.unique();
            //去掉前后空格不能为空
            if(this.obj.value.replace(/(^\s*)|(\s*$)/g,"") == ""){ return;}
            //判断数组中是否含有输入的关键字
            try{
                var reg = new RegExp("("+ this.obj.value +")","i"); //输入"aaa" 则 reg = /(aaa)/i
            }catch(e){
                alert(e.message); 
            }
            var div_index = 0;  //记录匹配索引个数
            for (var i = 0; i < valueArr.length; i++) {
                if(reg.test(valueArr[i])){
                    var div = document.createElement("div");
                    div.className = "auto_out";
                    div.seq = valueArr[i];
                    div.index = div_index;
                    div.innerHTML = valueArr[i].replace(reg,"$1");
                    this.autoObj.appendChild(div);
                    setClass.removeClass(this.autoObj,"hidden");
                    div_index++;
                    if(div_index == 1) {
                        setClass.addClass(this.autoObj.firstChild,"on");
                        this.index = 0;
                    }
                    div.onmouseover = function(){
                        This.autoOnmouseover(this.index);
                    }
                    div.onclick = this.setValue(This);
                }
            }
        }else{
            this.pressKey(event);
        }
        window.onresize = Bind(This);
    }
}

例子链接：http://pan.baidu.com/s/1gfLU4Mn

其他：
select框输入自动补全

例子链接：http://pan.baidu.com/s/1qYrldve