<script language="javascript">
function checked(){
if(document.form1.t1.value==""){alert('t1不能为空');document.form1.t1.focus();return false}
return true;
}
</script>
<form id="form1" name="form1" method="post" action="" onsubmit="return checked();">
<input name="t1" type="text" id="t1" />
<input type="submit" name="Submit" value="Submit" />
</form>稍微简便的写法：
<script language="javascript">
function checked(obj){
if(obj.t1.value==""){alert('t1不能为空');obj.t1.focus();return false}
return true;
}
</script>
<form id="form1" name="form1" method="post" action="" onsubmit="return checked(this);">
<input name="t1" type="text" id="t1" />
<input type="submit" name="Submit" value="Submit" />
</form>最简洁的写法：
<script language="javascript">
function checked(obj){
with(obj){
if(t1.value==""){alert('t1不能为空');t1.focus();return false}
}
return true;
}
</script>
<form id="form1" name="form1" method="post" action="" onsubmit="return checked(this);">
<input name="t1" type="text" id="t1" />
<input type="submit" name="Submit" value="Submit" />
</form>
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