Because you're telling the regex engine to match a line that contains the word 'is' only.

^ stands for a beginning of a line, while $ stands for the end of a line.

so unless you have a line that contains only 'is' it won't match

Your regex is better written as /\bis\b/are/g;

In reply to Re: regex is not producing desired output by ahmad
in thread regex is not producing desired output by manishrathi

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