<input type="text" name="mytxt" value=" 12345678 " />
 
<input type="button" name="cmd1" onclick="mytxt2.value=mytxt.value.trim()" value="去兩邊的空格"/> 
<input type="text" name="mytxt2"/>
 
<input type="button" name="cmd1" onclick="mytxt3.value=mytxt.value.ltrim()" value="去左邊的空格"/> 
<input type="text" name="mytxt3"/>
 
<input type="button" name="cmd1" onclick="mytxt4.value=mytxt.value.rtrim()" value="去右邊的空格"/> 
<input type="text" name="mytxt4"/>
 
<script language="javascript"> 
String.prototype.trim=function(){ 
return this.replace(/(^\s*)|(\s*$)/g, ""); 
} 
String.prototype.ltrim=function(){ 
return this.replace(/(^\s*)/g,""); 
} 
String.prototype.rtrim=function(){ 
return this.replace(/(\s*$)/g,""); 
} 
</script>

<script type="text/javascript"> 
function trim(str){ //刪除左右兩端的空格 
return str.replace(/(^\s*)|(\s*$)/g, ""); 
} 
function ltrim(str){ //刪除左邊的空格 
return str.replace(/(^\s*)/g,""); 
} 
function rtrim(str){ //刪除右邊的空格 
return str.replace(/(\s*$)/g,""); 
} 
</script>