<form name="tFrm" action="" method="post">
<input type="text" name="abc" value="2">
<input type="text" name="abc" value="3">
<input type="text" name="abc" value="4">
<input type="text" name="abc" value="5">
</form>
<script language="javascript">
alert(tFrm.abc.length);
</script>
<input type="text" name="abc" value="2">
<input type="text" name="abc" value="3">
<input type="text" name="abc" value="4">
<input type="text" name="abc" value="5">
</form>
<script language="javascript">
alert(tFrm.abc.length);
</script>
<input type="text" name="abc[0]" value="2">
<input type="text" name="abc[1]" value="3">
<input type="text" name="abc[2]" value="4">
<input type="text" name="abc[3]" value="5">
</form>
<script language="javascript">
alert(tFrm.elements.length);
</script>
<form name="tFrm" action="" method="post">
<input type="text" name="abc" value="2">
<input type="text" name="abc" value="3">
<input type="text" name="abc" value="4">
<input type="text" name="abc" value="5">
</form>
<script language="javascript">
alert(tFrm.abc.length);
</script>