using php preg_replace to change html link's href attribute

php preg-replace

Instead of any char . use any not (^) quote [^"]

echo preg_replace('/<a(.*)href="([^"]*)"(.*)>/','<a$1href="javascript:alert(\'Test\');"$3>',$string_of_text);

php preg-replace

Just use the greedy operator in your regex like this:

'/<a(.*?)href="(.*?)"(.*?)>/'

php preg-replace

Slight modifications to Aurelio De Rosa's answer:

'/<a(.*?)href=(["\'])(.*?)\\2(.*?)>/i'

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