JavaScript自定义Select组件：支持键盘导航与首字母筛选
本文介绍了一个基于JavaScript实现的自定义Select组件，支持通过键盘上下键选择选项、首字母快速筛选以及回车键确认取值。组件包含GetNewSelectStr和makeSelectBox两个核心函数，通过动态生成HTML表格结构模拟下拉列表，并结合事件监听实现交互逻辑，适用于需要增强原生Select体验的场景。
组件调用与参数说明
调用该组件时，可按照以下方式进行初始化：
1，tempStr=GetNewSelectStr(dataTable.value,"select"+rowIndex,true);
2,makeSelectBox("select"+rowIndex,tempStr,value,obj);
tempStr表示返回的下拉列表框体HTML字符串。
dataTable.value表示数据源，此处示例中为一张数据表。
"select"+rowIndex表示当前Select的ID号，由于页面可能存在多个Select，因此ID号是动态生成的。
true表示控制单击时是否出现下拉框体的标识。
value表示初始时显示在Select输入框中的值。
obj表示要显示Select的目标对象。
源代码如下：
核心功能实现代码
<script type="text/javascript">
var tempStr=GetNewSelectStr(dataTable.value,"select"+rowIndex,true);
makeSelectBox("select"+rowIndex,tempStr,value,obj);
var nowOpenedSelectBox = "";
var mousePosition = "";
var userList=null;
function selectThisValue(thisId,thisIndex,thisValue,thisString) {
var objId = thisId;
var nowIndex = thisIndex;
var valueString = thisString;
var sourceObj = $(objId);
var nowSelectedValue = document.getElementById(nowIndex+thisId).innerHTML;
hideOptionLayer(objId);
if (sourceObj) sourceObj.value = nowSelectedValue;
settingValue(objId,valueString);
selectBoxFocus(objId);
if (sourceObj.onchange) sourceObj.onchange();
}
function settingValue(thisId,thisString) {
var objId = thisId;
var valueString = thisString;
var selectedArea = document.getElementById(objId+"selectBoxSelectedValue");
if (selectedArea) {
if(navigator.appName.indexOf("Explorer") > -1){
selectedArea.innerText = valueString;
}
else{
selectedArea.textContent = valueString;
}
}
}
var l=0;
//显示下拉框中的值
function viewOptionLayer(thisId,Istask,flag) {
var objId = thisId;
var selectInfo="";
var optionHeight = 18; // 高
var optionMaxNum = 7; //
var optionInnerLayerHeight = "";
var selectBoxWidth =130;
var selectBoxHeight =17;
l=userList.Rows.length;
var optionLayer = document.getElementById(objId+"selectBoxs");
if(optionLayer.innerHTML=="")
{
if (l > optionMaxNum) optionInnerLayerHeight = "height:"+ (optionHeight * optionMaxNum) + "px";
selectInfo = "<table class='selectTable' id='" + objId + "selectBoxOptionLayer' cellpadding='0' cellspacing='0' border='0' style='position:absolute;z-index:100;'>";
if(Istask=="true")
{
selectInfo += " <tr>";
selectInfo += " <td height='" + selectBoxHeight + "' style='cursor:hand;' onClick=\"hideOptionLayer('"+ objId + "')\"></td>";
selectInfo += " </tr>";
selectInfo += " <tr>";
selectInfo += " <td style='height:2px;overflow:hidden;'></td>";
selectInfo += " </tr>";
}
else
{
selectInfo += " <tr style='height:24px;'>";
selectInfo += " <td height='" + selectBoxHeight + "' style='cursor:hand;' onClick=\"hideOptionLayer('"+ objId + "')\"></td>";
selectInfo += " </tr>";
}
selectInfo += " <tr style='height:17px;line-height:17px;border:none;'>";
selectInfo += " <td>";
selectInfo += " <div id='"+objId+"viewOptions' class='selectBoxOptionInnerLayer' style='width:" + selectBoxWidth + "px;" + optionInnerLayerHeight + "'>";
selectInfo += " <table class='selectTable' cellpadding='0' cellspacing='0' border='0' width='98%'>";
for (var i=0 ; i < l ; i++)
{
var nowValue = userList.Rows[i][userList.Columns[0].Name];
var nowText = userList.Rows[i][userList.Columns[0].Name];
if(Istask=="true")
{
selectInfo += " <tr>";
}
else
{
selectInfo += " <tr style='height:17px;line-height:17px; border:none;'>";
}
selectInfo += " <td id='"+i+objId+"' onMouseOver=\"resetStyle('"+objId+"');this.style.backgroundColor='#2c59aa';this.style.color='#ffffff';return true;\" onMouseOut=\"this.style.backgroundColor='#FFFFFF';this.style.color='#253449';return true;\" height='" + optionHeight + "' class='selectBoxOption' onMouseOver=\"this.className='selectBoxOptionOver'\" onMouseOut=\"this.className='selectBoxOption'\" onClick=\"selectThisValue('"+ objId + "'," + i + ",'" + nowValue + "','" + nowText + "')\" style='cursor:hand;'>" + nowText + "</td>";
// selectInfo += " <input type='hidden' id='"+ objId + "SelectBoxOptionValue" + i + "' value='" + nowValue + "'/>";
selectInfo += " </tr>";
}
selectInfo += " </table>";
selectInfo += " </div>";
selectInfo += " </td>";
selectInfo += " </tr>";
selectInfo += "</table>";
optionLayer.innerHTML=selectInfo;
}
if (flag && optionLayer.style.display=="none"){ optionLayer.style.display = "";optionLayer.focus();}
else
{
optionLayer.style.display = "none";
if(document.getElementById("level"))
{
document.getElementById("level").style.display="";
}
if(document.getElementById("priority"))
{
document.getElementById("priority").style.display="";
}
}
if(!flag){optionLayer.style.display = "";optionLayer.focus();}
for(var i=0;i<count;i++)
{
if(document.getElementById("select"+i+""+"viewOptions"))
{
document.getElementById("select"+i+""+"viewOptions").style.display="none";
}
}
document.getElementById(objId+"viewOptions").style.display="";
if(document.getElementById("level"))
{
document.getElementById("level").style.display="none";
}
if(document.getElementById("priority"))
{
document.getElementById("priority").style.display="none";
}
nowOpenedSelectBox = objId;
setMousePosition("inBox");
}
//支持首字母筛选、回车键取值、上下键选值功能
function firstLetter(thisId){
var count=0;
var selectedVal="";
if(document.getElementById(thisId+"viewOptions").style.display=="")
{
document.getElementById(thisId+"viewOptions").focus();
var asciiCode=String.fromCharCode(event.keyCode).toLowerCase();
var selectValue="";
if(event.keyCode==38)
{
for(var i=0;i<l;i++)
{
if(document.getElementById(i+thisId).className=="selectBoxOptionOver" && i>0)
{
document.getElementById(i+thisId).style.backgroundColor='#ffffff';
document.getElementById(i+thisId).style.color='#253449';
document.getElementById(i+thisId).className='selectBoxOption';
document.getElementById((i-1)+thisId).style.backgroundColor='#2c59aa';
document.getElementById((i-1)+thisId).style.color='#ffffff';
document.getElementById((i-1)+thisId).className='selectBoxOptionOver';
document.getElementById(thisId+"viewOptions").scrollTop= (i-1)*20;
count=1;
break;
}
}
if(count==0)
{
document.getElementById((l-1)+thisId).style.backgroundColor='#2c59aa';
document.getElementById((l-1)+thisId).style.color='#ffffff';
document.getElementById((l-1)+thisId).className='selectBoxOptionOver';
}
}
if(event.keyCode==40)
{
for(var i=0;i<l;i++)
{
if(document.getElementById(i+thisId).className=="selectBoxOptionOver" && i<l-1)
{
document.getElementById(i+thisId).style.backgroundColor='#ffffff';
document.getElementById(i+thisId).style.color='#253449';
document.getElementById(i+thisId).className='selectBoxOption';
document.getElementById((i+1)+thisId).style.backgroundColor='#2c59aa';
document.getElementById((i+1)+thisId).style.color='#ffffff';
document.getElementById((i+1)+thisId).className='selectBoxOptionOver';
if(i>10)
{
document.getElementById(thisId+"viewOptions").scrollTop= (i+1)*19;
}
else
{
document.getElementById(thisId+"viewOptions").scrollTop= (i+1)*10;
}
count=1;
break;
}
}
if(count==0)
{
document.getElementById(0+thisId).style.backgroundColor='#2c59aa';
document.getElementById(0+thisId).style.color='#ffffff';
document.getElementById(0+thisId).className='selectBoxOptionOver';
}
}
if(event.keyCode==13)
{
for(var i=0;i<l;i++)
{
if(document.getElementById(i+thisId).className=="selectBoxOptionOver")
{
selectedVal=document.getElementById(i+thisId).innerHTML;
var sourceObj = $(thisId);
hideOptionLayer(thisId);
if (sourceObj) sourceObj.value = selectedVal;
settingValue(thisId,selectedVal);
selectBoxFocus(thisId);
if (sourceObj.onchange) sourceObj.onchange();
document.getElementById(thisId+"viewOptions").style.display="none";
if(document.getElementById("level"))
{
document.getElementById("level").style.display="";
}
if(document.getElementById("priority"))
{
document.getElementById("priority").style.display="";
}
break;
}
}
}
for(var i=0 ; i < l ; i++)
{
selectValue=document.getElementById(i+thisId).innerHTML;
if(asciiCode==selectValue.substring(0,1))
{
resetStyle(thisId);
document.getElementById(i+thisId).style.backgroundColor='#2c59aa';
document.getElementById(i+thisId).style.color='#ffffff';
document.getElementById(i+thisId).className='selectBoxOptionOver';
document.getElementById(thisId+"viewOptions").scrollTop= i*19;
break;
}
}
}
}
//清除被选中的下拉列表值的样式
function resetStyle(thisId){
for(var i=0;i<l;i++)
{
document.getElementById(i+thisId).style.backgroundColor='#ffffff';
document.getElementById(i+thisId).style.color='#253449';
document.getElementById(i+thisId).className='selectBoxOption';
}
}
//隐藏下拉框
function hideOptionLayer(thisId) {
var objId = thisId;
var optionLayer = document.getElementById(objId+"selectBoxs");
if (optionLayer) optionLayer.style.display = "none";
if(document.getElementById("level"))
{
document.getElementById("level").style.display="";
}
if(document.getElementById("priority"))
{
document.getElementById("priority").style.display="";
}
}
function setMousePosition(thisValue) {
var positionValue = thisValue;
mousePosition = positionValue;
}
function clickMouse() {
if (mousePosition == "out") hideOptionLayer(nowOpenedSelectBox);
}
function selectBoxFocus(thisId) {
var objId = thisId;
var obj = document.getElementById(objId + "selectBoxSelectedValue");
obj.className = "selectBoxSelectedAreaFocus";
obj.focus();
}
function selectBoxBlur(thisId) {
var objId = thisId;
var obj = document.getElementById(objId + "selectBoxSelectedValue");
obj.className = "selectBoxSelectedArea";
}
function hiddenOptions(thisId){
document.getElementById(thisId+"viewOptions").style.display="none";
if(document.getElementById("level"))
{
document.getElementById("level").style.display="";
}
if(document.getElementById("priority"))
{
document.getElementById("priority").style.display="";
}
}
function makeSelectBox(index,newSelect,value,obj) {
newSelect=newSelect.replace(/(select0)/g,index);
$(obj).html(newSelect);
settingValue(index,value);
}
function GetNewSelectStr(table,index,IsTask){
userList=table;
var downArrowSrc = "../images/sanjiao.gif"; //三角
var downArrowSrcWidth = 16; //宽
var selectBoxWidth =130;
var selectBoxHeight =17;
newSelect="<div id='" + index + "selectBoxs' style='position:absolute;z-index:100;display:none;' onMouseOut=\"setMousePosition('out')\" onkeydown=\"firstLetter('"+ index + "')\"></div>"
newSelect += "<table class='selectTable' cellpadding='0' cellspacing='1' border='0' onClick=\"viewOptionLayer('"+ index + "','"+ IsTask + "',true)\" style='cursor:hand;height:18px;line-height:18px;' onkeydown=\"firstLetter('"+ index + "')\">";
newSelect += " <tr>";
newSelect += " <td>";
newSelect += " <table class='selectTable' cellpadding='0' cellspacing='0' border='0' style='height:18px;border:1px solid #9BB8C8;'>";
if(IsTask)
{
newSelect += " <tr>";
newSelect += " <td><div id='" + index + "selectBoxSelectedValue' name='selectBoxSelectedValue' class='selectBoxSelectedArea' style='width:" + (selectBoxWidth-downArrowSrcWidth-3)+ "px;height:" + selectBoxHeight + "px;overflow:hidden;' onBlur=\"selectBoxBlur('" + index + "');ValueEditd(this)\" onchange='ValueEditd(this)'></div></td>";
}
else
{
newSelect += " <tr style='height:18px;line-height:17px;'>";
newSelect += " <td><div id='" + index + "selectBoxSelectedValue' name='selectBoxSelectedValue' class='selectBoxSelectedArea' style='width:" + (selectBoxWidth-downArrowSrcWidth-4)+ "px;overflow:hidden;' onBlur=\"selectBoxBlur('" + index + "');\"></div></td>";
}
newSelect += " <td><img src='" + downArrowSrc + "' width='" + downArrowSrcWidth + "' border='0'></td>";
newSelect += " </tr>";
newSelect += " </table>";
newSelect += " </td>";
newSelect += " </tr>";
newSelect += "</table>";
return newSelect ;
}
</script>
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