Probably regurgitating the instructions, but you being asked to use capture groups to satisfy the test.
basically how capture groups work is that the stuff you match within the parenthesis “( )”, are sort of stored in a temporary array. You can then access whatever you match with that capture group with in index, starting at 1.
so in the example:
let repeatStr = “regex regex”;
let repeatRegex = /(\w+)\s\1/;
repeatRegex.test(repeatStr); // Returns true
repeatStr.match(repeatRegex); // Returns [“regex regex”, “regex”]
The regex is first finding something that matches the longest string of word characters. Then find a space. Then, instead of typing out the match again, simply reuses the match with
Now if you’re wondering about the last line, that’s just the nature of what match returns.