const regex = /((\[\d+:\d+:\d+ \w+\][\w ]+:)|(\[\d+:\d+:\d+ \w+ \| \w+ \d+:\d+:\d+ \w+\][\w ]+:))([ \w'.,]+)/g;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('((\\[\\d+:\\d+:\\d+ \\w+\\][\\w ]+:)|(\\[\\d+:\\d+:\\d+ \\w+ \\| \\w+ \\d+:\\d+:\\d+ \\w+\\][\\w ]+:))([ \\w\'.,]+)', 'g')
const str = `[9:14:51 AM] Jeff: If you could just do me a favoure and list all these concerns and in a mail and if you have any ideas that you might want to implement so that I can get everybodys notes.
[9:14:56 AM] Timmy: in terms of websites or domains or DNSs I have no clue about setup
[9:15:19 AM | Edited 9:15:25 AM] Jeff: That, I will get Sam and Frodo involved in
[9:16:01 AM] Jeff: I am stepping out quickly`;
const subst = ``;
// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);
console.log('Substitution result: ', result);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions