Groups and ranges indicate groups and ranges of expression characters. The regular expression x|y matches either "x" or "y".
const REGEXP = /blue|red/
"red flag".match(REGEXP) // red
"blue flag".match(REGEXP) // blue
// Matches "blue" in "blue flag" and "red" in "red flag".
Create a regular expression to match all red flag and blue flag in a string. You must use | in your expression. Flags can come in any order.
"red flag blue flag".match(REGEXP) ➞ ["red flag", "blue flag"]
"yellow flag red flag blue flag green flag".match(REGEXP) ➞ ["red flag", "blue flag"]
"pink flag red flag black flag blue flag green flag red flag ".match(REGEXP) ➞ ["red flag", "blue flag", "red flag"]