在textarea输入Tab - 51windows.Net

<script>
function editTab()
{

	var code, sel, tmp, r
	var tabs=""
	event.returnValue = false
	sel =event.srcElement.document.selection.createRange()
	r = event.srcElement.createTextRange()

	switch (event.keyCode)
	{
		case (8)	:
			if (!(sel.getClientRects().length > 1))
			{
				event.returnValue = true
				return
			}
			code = sel.text
			tmp = sel.duplicate()
			tmp.moveToPoint(r.getBoundingClientRect().left, sel.getClientRects()[0].top)
			sel.setEndPoint("startToStart", tmp)
			sel.text = sel.text.replace(/^\t/gm, "")
			code = code.replace(/^\t/gm, "").replace(/\r\n/g, "\r")
			r.findText(code)
			r.select()
			break
		case (9)	:
			if (sel.getClientRects().length > 1)
			{
				code = sel.text
				tmp = sel.duplicate()
				tmp.moveToPoint(r.getBoundingClientRect().left, sel.getClientRects()[0].top)
				sel.setEndPoint("startToStart", tmp)
				sel.text = "\t"+sel.text.replace(/\r\n/g, "\r\t")
				code = code.replace(/\r\n/g, "\r\t")
				r.findText(code)
				r.select()
			}
			else
			{
				sel.text = "\t"
				sel.select()
			}
			break
		case (13)	:
			tmp = sel.duplicate()
			tmp.moveToPoint(r.getBoundingClientRect().left, sel.getClientRects()[0].top)
			tmp.setEndPoint("endToEnd", sel)

			for (var i=0; tmp.text.match(/^[\t]+/g) && i<tmp.text.match(/^[\t]+/g)[0].length; i++)	tabs += "\t"
			sel.text = "\r\n"+tabs
			sel.select()
			break
		default		:
			event.returnValue = true
			break
	}
}
</script>
<textarea rows="24" onkeydown="editTab()" style="width:100%" name="filetext" cols="80"></textarea>