Find if word exists between two words and replace that word in JavaScript

I have something like:

Some MY_WORD stupid txt='other text MY_WORD' and another MY_WORD  stupid text and txt='something else MY_WORD' and also txt='here nothing to replace' and here txt='again to replace MY_WORD here'

I want to replace MY_WORD with OTHER_WORD but only if it is inside txt=' and '

/(?<=txt='.*)MY_WORD(?=.*')/g


Some MY_WORD stupid txt='other text OTHER_WORD' and another MY_WORD  stupid text and txt='something else OTHER_WORD' and also txt='here nothing to replace' and hexe txt='again to replace OTHER_WORD here'

But look behind is not supported in all browsers, so it is not good approach.

A tried with this but even it says there are groups of matches, I $3 is empty.

(txt=')((.*)(MY_WORD))?