Maison >interface Web >js tutoriel >Exemple détaillé de la façon d'ajouter des numéros de ligne aux zones de texte Textarea en JavaScript
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>
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