編程（Programming）是編定程序的中文簡稱，就是讓計算機代碼解決某個問題，對某個計算體系規定一定的運算方式，使計算體系按照該計算方式運行，并最終得到相應結果的過程。為了使計算機能夠理解（understand）人的意圖，人類就必須將需解決的問題的思路、方法和手段通過計算機能夠理解的形式告訴計算機，使得計算機能夠根據人的指令一步一步去工作，完成某種特定的任務。這種人和計算體系之間交流的過程就是編程。
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<TITLE>滑動條-本站（www.xue51.com）</title>
<META NAME="Generator" CONTENT="EditPlus">
<META NAME="Author" CONTENT="">
<META NAME="Keywords" CONTENT="">
<META NAME="Description" CONTENT="">
<script language="javascript">
var objContainsDiv;
var objTrackBar;
var objTrackPath;
var objScaleDiv;
var scaleNumber = 20;
var scaleLenth; //刻度長度
var vLeft;
var vaildLength;//滑塊能夠移動的有效長度
function contentLoad()
{
objContainsDiv = trackDiv;//容器
objTrackBar = createTrack();
objTrackBar = objContainsDiv.appendChild(objTrackBar);
objTrackPath = trackDegree;
objTrackBar.onmousedown = trackBarBeforeMove;
objTrackBar.onmouseup = trackBeforeMouseup;
objTrackPath.onclick = setPos;vaildLength =
parseInt(objContainsDiv.offsetWidth) -
parseInt(objTrackBar.offsetWidth) - 2;
scaleLenth = Math.round(parseInt(objContainsDiv.offsetWidth)/scaleNumber);
//手動生成刻度線
for(var i=0;i<scaleNumber - 1;i++){
objScaleDiv = this.document.createElement("
<div style='position:absolute;left:50;top:13;
font-size:4pt;font-weight:lighter;color:#999999;width:3:'/>");
objScaleDiv = objContainsDiv.appendChild(objScaleDiv);
with(objScaleDiv){
style.left = scaleLenth*(i + 1);
innerText = "|";
}
}
}
function createTrack(){ //創建滑動條
var objBarContainsDiv;
objBarContainsDiv = this.document.createElement("
<div style='position:absolute;left:0;top:0;height:16;width:11;z-index:2;'/>");
//創建矩形區域
var objBarTop = this.document.createElement("
<div style='position:absolute;left:0;top:0;height:10;width:11;
font-size:1px;border-top:solid 1px #999999;border-right:solid 1px #666666;
border-left:solid 1px #cccccc;z-index:2;background:#cccccc;'>");
objBarTop = objBarContainsDiv.appendChild(objBarTop);
var objPointDiv;
var iScale = 0;
for(var i=0;i<6;i++){ //創建紅色標識區域，用來指向刻度
objPointDiv = this.document.createElement("
<div style='position:absolute;background:red;font-size:1px;
z-index:2;border-right:solid 1px #990000;'>");
iScale = i + 1;
with(objPointDiv){
style.left = iScale;
style.top = parseInt(objBarTop.style.pixelHeight) + (iScale - 1);
if((parseInt(objBarTop.style.pixelWidth) - 2*iScale)<0){
break;
}
style.width = parseInt(objBarTop.style.pixelWidth) - 2*iScale;
}
objPointDiv = objBarContainsDiv.appendChild(objPointDiv);
}
return objBarContainsDiv;
}
function setPos(){ //單擊滑動條時，設置滑動條位置
trackBeforeMove();
trackLevel.innerText = Math.round(parseInt(objTrackBar.style.left)
*100/vaildLength) + "%";//顯示刻度數
}
function trackBarBeforeMove(){//移動滑動條前的準備
vLeft = window.event.x - objTrackBar.style.pixelLeft;
objTrackBar.style.background = "#dddddd";//背景
objTrackBar.setCapture(); //鼠標
objTrackBar.attachEvent("onmousemove", trackBeforeMove);
//動態添加移動事件
}
function trackBeforeMove(){//滑塊移動中
var leftPoint;
var pointDividLength;
var vMousePositionX;
if((event.x - objContainsDiv.offsetLeft - 8) > vaildLength ||
event.x<objContainsDiv.offsetLeft) return;vMousePositionX =
parseInt(event.x) - objContainsDiv.offsetLeft;
leftPoint = Math.floor(vMousePositionX/scaleLenth);
//左邊最近的點序號
pointDividLength = leftPoint*scaleLenth + scaleLenth/2;
window.status = "leftPoint:" + leftPoint + " [vMousePositionX:" +
vMousePositionX + " pointDividLength:" + pointDividLength + "]";
if(vMousePositionX < pointDividLength){ //粘連到左邊點
objTrackBar.style.left = leftPoint*scaleLenth;
}
if(vMousePositionX > pointDividLength){ //粘連到右邊點
objTrackBar.style.left = (leftPoint+1)*scaleLenth;
}
if(parseInt(objTrackBar.style.left)>vaildLength){//移到了右邊界
objTrackBar.style.left = vaildLength;
}
if(parseInt(objTrackBar.style.left)<0){ //移到了左邊界
objTrackBar.style.left = 0;
}
trackLevel.innerText = Math.round(parseInt
(objTrackBar.style.left)*100/vaildLength) + "%";
}
function trackBeforeMouseup(){ //滑動結束，解除綁定
if(parseInt(trackLevel.innerText.replace("%",""))>100){
objTrackBar.style.left = vaildLength;
trackLevel.innerText = "100%";//不能超出最大刻度100
}else if(parseInt(trackLevel.innerText.replace("%",""))<0){
objTrackBar.style.left = 0;
trackLevel.innerText = "0%";//不能小于最大刻度0
}
objTrackBar.detachEvent("onmousemove", trackBeforeMove);
//撤銷事件綁定
objTrackBar.style.background = "#cccccc";
//改變背景色
objTrackBar.releaseCapture(); //釋放鼠標
}
</script>
</HEAD>
<BODY onload="contentLoad()">
<div id="trackDiv" style="position:absolute;left:100;top:50;
border:solid 0px #cccccc;width:700;height:23;background:#dddddd;">
<hr id="trackDegree" size="1" color="#cccccc"
style="position:absolute;top:16;height:3;border:groove 1px #eeeeee;
background:#666666;z-index:1;">
</div>
<span id="trackLevel" style="position:absolute;left:100;top:30;
width:50;font-size:9pt;color:red;">0%</span>
</BODY>
</HTML>
本例的重點在于所有的刻度、滑動條、滑動條標識都是動態創建的。在“createTrack”方法中，“objBarTop”屬性是創建的滑動條標識的上部分，“objPoimDiv”是創建在滑動條下部的紅色指標，通過其可以輕松地看到滑動條的當前刻度。
