Validate US Telephone Numbers-lookahead

JavaScript
3

Hello reinelic,

I remember how much skull sweat learning regex cost me (both the first time in PERL, years ago, and now again for web dev). Here are the links I found helpful when learning them, especially regexr.

Regexr: Testing site, much like codepen or jsfiddle - uses coloring and explains step-by-step what is going on in what you write

Quick table of regex operators

In-depth tutorial, looks very granularly at the regex engine, uses colors to illustrate concepts

To get you started on the path to regex mastery, here’s a regexr for the givens you’ve provided