JS实现文本中查找并替换字符

效果图：

代码如下，复制即可使用：

<!DOCTYPE html>
<html>
<head><style type="text/css">*{font-family:"微软雅黑";font-size:16px;margin:0;padding:0;letter-spacing:3px;line-height:22px;}#wrap{width:500px;height:300px;margin:20px auto;position:relative;}#text{width:500px;height:300px;border:1px solid green;}#result{width:500px;position:absolute;left:0px;top:0px;display:none;}input{width:100px;height:40px;margin-top:5px;}span{background-color:yellow;}</style>
</head>
<body><div id="wrap"><div id="result"></div><textarea id="text" placeholder="请在此输入文本。。。。"></textarea><input type="text" id="val" placeholder="被查找字符"/>——<input type="text" id="new_val" placeholder="替换后字符"/>&nbsp;&nbsp;&nbsp;<input type="button" id="btnFind" value="替换"/>&nbsp;&nbsp;&nbsp;<input type="button" value="重置" id="reset"/></div><script type="text/javascript">function replace(){var inner=null;var txt=document.getElementById('text').value.toString();var val=document.getElementById('val').value.toString();var newVal=document.getElementById('new_val').value.toString();newInner="<span>" newVal "</span>";for(var i=0;i<=txt.length-val.length;i  ){if(txt==""||val=="") {alert("请输入内容！");return false;}if(txt.length<val.length) {return false;}if(i val.length>=txt.length){if(txt.substring(i)==val){inner=txt.split('');inner.splice(i,val.length,newInner);txt=inner.join("");i=i newInner.length-1;}}else {if(txt.substring(i,i val.length)==val) {inner=txt.split('');inner.splice(i,val.length,newInner);txt=inner.join("");i=i newInner.length-1;}}}document.getElementById("result").innerHTML=txt;document.getElementById("text").value=null;document.getElementById("text").placeholder="";document.getElementById("result").style.display="block";}document.getElementById('btnFind').onclick=function(){replace();}document.getElementById('reset').onclick=function(){document.getElementById("result").style.display="none";document.getElementById("val").value=null;document.getElementById("new_val").value=null;document.getElementById("text").placeholder="请在此输入文本。。。。";}</script>
</div>
</body>
</html>