en.javascript.info/9-regular-expressions/13-regexp-alternation/01-find-programming-language/solution.md

The first idea can be to list the languages with | in-between.

But that doesn't work right:

let regexp = /Java|JavaScript|PHP|C|C\+\+/g;

let str = "Java, JavaScript, PHP, C, C++";

alert( str.match(regexp) ); // Java,Java,PHP,C,C

The regular expression engine looks for alternations one-by-one. That is: first it checks if we have match:Java, otherwise -- looks for match:JavaScript and so on.

As a result, match:JavaScript can never be found, just because match:Java is checked first.

The same with match:C and match:C++.

There are two solutions for that problem:

1. Change the order to check the longer match first: pattern:JavaScript|Java|C\+\+|C|PHP.
2. Merge variants with the same start: pattern:Java(Script)?|C(\+\+)?|PHP.

In action:

let regexp = /Java(Script)?|C(\+\+)?|PHP/g;

let str = "Java, JavaScript, PHP, C, C++";

alert( str.match(regexp) ); // Java,JavaScript,PHP,C,C++