一次精简JS代码过程

<script language="javascript">
function ShowDivA()
{
	document.getElementById("DivA").style.display = "block";
	document.getElementById("DivB").style.display = "none";
	document.getElementById("DivC").style.display = "none";
}
function ShowDivB()
{
	document.getElementById("DivA").style.display = "none";
	document.getElementById("DivB").style.display = "block";
	document.getElementById("DivC").style.display = "none";
}
function ShowDivC()
{
	document.getElementById("DivA").style.display = "none";
	document.getElementById("DivB").style.display = "none";
	document.getElementById("DivC").style.display = "block";
}
</script>
<div id="DivA" style="display:none;">DivA</div>
<div id="DivB" style="display:none;">DivB</div>
<div id="DivC" style="display:none;">DivC</div>
<input type="button" onclick="ShowDivA();" value="显示A" />
<input type="button" onclick="ShowDivB();" value="显示B" />
<input type="button" onclick="ShowDivC();" value="显示C" />

<script language="javascript">
function ShowDiv(str)
{
	if(str=="DivA")
	{
		document.getElementById("DivA").style.display = "block";
		document.getElementById("DivB").style.display = "none";
		document.getElementById("DivC").style.display = "none";
	}
	else if(str=="DivB")
	{
		document.getElementById("DivA").style.display = "none";
		document.getElementById("DivB").style.display = "block";
		document.getElementById("DivC").style.display = "none";
	}
	else if(str=="DivC")
	{
		document.getElementById("DivA").style.display = "none";
		document.getElementById("DivB").style.display = "none";
		document.getElementById("DivC").style.display = "block";
	}
}
</script>
<div id="DivA" style="display:none;">DivA</div>
<div id="DivB" style="display:none;">DivB</div>
<div id="DivC" style="display:none;">DivC</div>
<input type="button" onclick="ShowDiv('DivA');" value="显示A" />
<input type="button" onclick="ShowDiv('DivB');" value="显示B" />
<input type="button" onclick="ShowDiv('DivC');" value="显示C" />

<script language="javascript">
function ShowDiv(obj)
{
	document.getElementById("DivA").style.display = "none";
	document.getElementById("DivB").style.display = "none";
	document.getElementById("DivC").style.display = "none";
	obj.style.display = "block";
}
</script>
<div id="DivA" style="display:none;">DivA</div>
<div id="DivB" style="display:none;">DivB</div>
<div id="DivC" style="display:none;">DivC</div>
<input type="button" onclick="ShowDiv(DivA);" value="显示A" />
<input type="button" onclick="ShowDiv(DivB);" value="显示B" />
<input type="button" onclick="ShowDiv(DivC);" value="显示C" />