本文实例讲述了JS给Textarea文本框添加行号的方法。分享给大家供大家参考。具体如下：
这里使用JS实现让Textarea文本框显示行号的功能，每一行的前面都会有下数字序号，如果用来显示代码的话，可以直接找到某一行，如果不显示行号，则还要自己手功去查，想要此功能，你只需设置好TextArea ID，并加入代码中的JavaScript代码部分即可，文本框的长宽则是由CSS来控制的，你可试着修改一下，长宽的显示要与JS相匹配。
运行效果截图如下：
在线演示地址如下：
http://demo.jb51.net/js/2015/js-textarea-show-row-num-codes/
具体代码如下：
<html>
<head>
<title>Js给文本框添加行号功能</title>
<style type="text/css">
#codeTextarea{width: 500px;height: 310px;}
.textAreaWithLines{font-family: courier;border: 1px solid #ddd;}
.textAreaWithLines textarea,.textAreaWithLines p{border: 0px;line-height: 120%;font-size: 12px;}
.lineObj{color: #666;}
</style>
<script type="text/javascript">
var lineObjOffsetTop = 2;
function createTextAreaWithLines(id)
{
var el = document.createElement("p");
var ta = document.getElementById(id);
ta.parentNode.insertBefore(el,ta);
el.appendChild(ta);
el.className="textAreaWithLines";
el.style.width = (ta.offsetWidth + 30) + "px";
ta.style.position = "absolute";
ta.style.left = "30px";
el.style.height = (ta.offsetHeight + 2) + "px";
el.style.overflow="hidden";
el.style.position = "relative";
el.style.width = (ta.offsetWidth + 30) + "px";
var lineObj = document.createElement("p");
lineObj.style.position = "absolute";
lineObj.style.top = lineObjOffsetTop + "px";
lineObj.style.left = "0px";
lineObj.style.width = "27px";
el.insertBefore(lineObj,ta);
lineObj.style.textAlign = "right";
lineObj.className="lineObj";
var string = "";
for(var no=1;no<20;no++){
if(string.length>0)string = string + "<br>";
string = string + no;
}
ta.onkeydown = function() { positionLineObj(lineObj,ta); };
ta.onmousedown = function() { positionLineObj(lineObj,ta); };
ta.onscroll = function() { positionLineObj(lineObj,ta); };
ta.onblur = function() { positionLineObj(lineObj,ta); };
ta.onfocus = function() { positionLineObj(lineObj,ta); };
ta.onmouseover = function() { positionLineObj(lineObj,ta); };
lineObj.innerHTML = string;
}
function positionLineObj(obj,ta)
{
obj.style.top = (ta.scrollTop * -1 + lineObjOffsetTop) + "px";
}
</script>
</head>
<body>
<form>
<textarea id="codeTextarea"></textarea>
</form>
<script type="text/javascript">
createTextAreaWithLines("codeTextarea");
</script>
</body>
</html>Das obige ist der detaillierte Inhalt vonDetailliertes Beispiel für das Hinzufügen von Zeilennummern zu Textarea-Textfeldern in JavaScript. Für weitere Informationen folgen Sie bitte anderen verwandten Artikeln auf der PHP chinesischen Website!
