How do I outdent by a specific amount of tabs? - regex

Question

I'm trying to create a function that I can use to outdent (versus indent) a specific amount.
Here is what I have so far. This removes all tabs at the beginning of the lines. I think I need to create a dynamic pattern or use a function but I'm stuck:
var outdentPattern:RegExp = /([\t ]*)(.+)$/gm;
function outdent(input:String, outdentAmount:String = "\t"):String {
var outdentedText:String = input.replace(outdentPattern, outdentAmount + "$2");
return outdentedText;
}
Here is test data:
<s:BorderContainer>
<html:htmlOverride><![CDATA[
<script>
var test:Boolean = true;
test = "string";
</script>]]>
</html:htmlOverride>
</s:BorderContainer>
The test would be remove one tab, remove two tabs, etc.
Expected results at one tab would be:
<s:BorderContainer>
<html:htmlOverride><![CDATA[
<script>
var test:Boolean = true;
test = "string";
</script>]]>
</html:htmlOverride>
</s:BorderContainer>
And two tabs:
<s:BorderContainer>
<html:htmlOverride><![CDATA[
<script>
var test:Boolean = true;
test = "string";
</script>]]>
</html:htmlOverride>
</s:BorderContainer>
And three tabs with the inner tabs (whitespace) collapsing down:
<s:BorderContainer x="110" height="160" width="240" y="52">
<html:htmlOverride><![CDATA[
<script>
var test:Boolean = true;
</script>
]]></html:htmlOverride>
</s:BorderContainer>
Interesting note:
The editor on SO is outdenting when you click code button when the code is already indented.

Answer 1

You could either construct a RegExp object from a template, or you could use the regular expression several times:
var temp:String = '^[\t ]{0,';
function outdent(input:String, amount:Number = 1):String {
return input.replace(new RegExp(temp + amount.toString() + '}', 'gm'), '');
}
Or:
var pattern:RegExp = /^[\t ]/gm;
function outdent(input:String, amount:Number = 1):String {
for (var i:Number = 0; i < amount; i++)
input = input.replace(pattern, '');
return input;
}