Variable with a regex in JavaScript

Regular expressions can be placed into variables. Let's look at an example. Let's say we have the following string:

javascriptlet str = 'aaa bbb ccc';

Let's say we have the following code with a regex:

javascriptlet res = str.replace(/\w+/, '!');

Let's move the regular expression into a variable:

javascriptlet reg = /\w+/;
let res = str.replace(reg, '!');

javascriptlet str = 'a aa aaa aaaa aaaa';
let res = str.replace(/a+/, '!');