There's a bug in your first regexp: You're using ',*' when I think you meant to use '.*'

Another potential bug is the fact that you're relying on $1 without first checking to see if a match succeeded. Bad dog.

Regarding your question, you might successfully get your regexp to match less by using the non-greedy modifier on the quantifier.

$var =~ /onChange\=\"\[(.*?)\]\"/;
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The '.*?' construct says to match as little as possible of any number of characters until the first ]" is reached.