Question

I’m trying to convert XML tags to uppercase, while preserving the case of attributes and text. So for example

<Mytag Category="Parent">Value1</Mytag>

Becomes

<MYTAG Category="Parent">Value1</MYTAG>

I have a regex which matches the XML tags correctly, but the upperCase function does not seem to be working.

myXmlElement.replace(/<(\/)*([a-zA-Z_0-9]+)([^>]*)>/g,"<$1" + "$2".toUpperCase() + "$3>")

I’ve also tried using String.prototype.toUpperCase.apply("$2"), as well as passing a function as the replace argument

myXmlElement.replace(/<[\/]*([a-zA-Z_0-9]+)[^>]*>/g,
                    function($1,$2,$3){return <$1 + $2.toUpperCase() + $3>})

But this doesn’t work, as $1,$2,$3 appear to refer to the entire matching elements ($1 = , $2 = )

I’m sure there is something trivial I am overlooking here, can anybody help out?

Answer 1

If you want to match the characters before and after your tag name, the need to be put into matching braces within the pattern:

var pattern = /<([\/]*)([a-zA-Z_0-9]+)([^>]*)>/g 
var newTag = myElement.replace(pattern, function(full, before, tag, after) { 
  return "<" before + tag.toUpperCase() + after + ">"
})

The replacement function will take the full matching expression as first argument. That’s why you simply may ignore it.
After that any matching brace of your pattern will be passed as a parameter.