一个简单的页面校验
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312"><title>Validate Demo</title><style>td{padding-left:5px;font-size:12px;}.red{color:red;padding-left:10px;}</style></head><body><form name="form1" method="post" action=""> <table width="500" border="0" align="center" cellspacing="1" bgcolor="#CCCCCC"> <tr bgcolor="#FFFFFF"> <td width="100">Text01</td> <td width="300"><input name="a1" type="text" id="a1"></td> <td> </td> </tr> <tr bgcolor="#FFFFFF"> <td>Text02</td> <td><input name="a2" type="text" id="a2"></td> <td> </td> </tr> <tr bgcolor="#FFFFFF" align="center"> <td colspan="3"><input type="button" name="Submit" value="DoCheck" onClick="doCheck()"></td> </tr> </table></form><script>function doCheck(){ var t=document.all; clearAllErr(); alert("will Start to check.....")if(t.a1.value==""){addErr(t.a1,"不能为空");}if(t.a2.value==""){addErr(t.a2,"不能为空");}}/*****清除所有错误信息**/function clearAllErr(){var tt = document.all.errspans;if(!IsJsObject(tt)) return ; if(tt.length > 1){for(var i=0;i<tt.length;i++){tt[i].innerHTML = "";}}else{tt.innerHTML = "";}} /*****增加错误信息*@fieldName 输入框id*@mesg 错误信息*/function addErr(fieldName, mesg){var newElement = document.createElement("SPAN");newElement.className = "red";newElement.id = "errspans";newElement.name = "errspans";if(fieldName.parentNode.lastChild.name != "errspans"){fieldName.parentNode.appendChild(newElement);}if(fieldName.parentNode.lastChild.innerHTML == ""){fieldName.parentNode.lastChild.innerHTML = mesg;}}/* *功能：判断是否输入参数对象是否存在 *参数：对象本身，比如document.all.inputName */function IsJsObject(obj) {try{if(typeof(obj) == 'object'){return true;}else{return false;}}catch(e){//alert(e.message);return false;}}</script></body></html>?