Regex for individual words in php

This is a simple check for words that you might want to check if the given string is this word or that word. Possible utilization could be: when you allow the user to upload file, you might want to get only certain type of file only like in the case of image jpeg, jpg, and gif only

if (preg_match('/jpeg|jpg|gif/i')){
   //do uploading
}else{
    $message = "supported file types are ...";
}

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