Question

I’m using this regular expression:

var regex = /\<.*?.\>/g

to match with this string:

var str = 'This <is> a string to <use> to test the <regular> expression'

using a simple match:

str.match(regex)

and, as expected, I get:

["<is>", "<use>", "<regular>"]

(But without the backslashes, sorry for any potential confusion)

How can I get the reverse result? i.e. what regular expression do I need that does not return those items contained between < and >?

I tried /(^\<.*?\>)/g and various other similar combos including square brackets and stuff. I’ve got loads of cool results, just nothing that is quite what I want.

Where I’m going with this: Basically I want to search and replace occurences of substrings but I want to exclude some of the search space, probably using < and >. I don’t really want a destructive method as I don’t want to break apart strings, change them, and worry about reconstructing them.

Of course I could do this ‘manually’ by searching through the string but I figured regular expressions should be able to handle this rather well. Alas, my knowledge is not where it needs to be!!

Answer 1

Here’s a way to do custom replacement of everything outside of the tags, and to strip the tags from the tagged parts http://jsfiddle.net/tcATT/

var string = 'This <is> a string to <use> to test the <regular> expression';
// The regular expression matches everything, but each val is either a
// tagged value (<is> <regular>), or the text you actually want to replace
// you need to decide that in the replacer function
console.log(str.replace( /[^<>]+|<.*?>/g, function(val){
    if(val.charAt(0) == '<' && val.charAt(val.length - 1) == '>') {
      // Just strip the < and > from the ends
      return val.slice(1,-1);
    } else {
      // Do whatever you want with val here, I'm upcasing for simplicity
      return val.toUpperCase(); 
    }
} ));​
// outputs: "THIS is A STRING TO use TO TEST THE regular EXPRESSION" 

To generalize it, you could use

function replaceOutsideTags(str, replacer) {
    return str.replace( /[^<>]+|<.*?>/g, function(val){
        if(val.charAt(0) == '<' && val.charAt(val.length - 1) == '>') {
          // Just strip the < and > from the ends
          return val.slice(1,-1);
        } else {
          // Let the caller decide how to replace the parts that need replacing
          return replacer(val); 
        }
    })
}
// And call it like
console.log(
    replaceOutsideTags( str, function(val){
        return val.toUpperCase();
    })
);