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Regular Expressions Tutorial

The purpose of this gist is to create a helpful walkthrough explaining the ins and outs of regular expressions. Regular expressions, or regex for short, are a series of special characters that define a search pattern. Essentially, a regular expression can be used to match a certain RexEx pattern against a string. This is very useful for pulling data and validating the results. This tutorial will follow the example below that can be used to match against an email address.

Summary

In this tutorial, I will break down the regular expression below that helps validate for a particular pattern; in this case, we will be validating an email address. This is useful because it looks for an email that matches the correct format via RegEx.

Matching Email-

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// Write a function that takes two strings and returns true if every word found in the second string is present in the 
// first string. You will be checking for both words and their frequency. Assume you'll need to worry about casing, 
// but the strings won't contain any punctuation. Assume neither string will be empty

var concertFlyer = function (magazine, flyer) {
    const arr = flyer.split(' ')
    let boolean = []
    arr.forEach(word => {
        if(magazine.indexOf(word) === -1) {
            boolean.push(false)

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/**
Youtube Interview Link: 
https://www.youtube.com/watch?v=vomuCMmoNyE&t=2628s


Write a function that takes two numbers and returns
the sum of those numbers
 */
function add(num1, num2) {
    let sum = num1 + num2

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function fizzBuzz(num) {
    let output = [];
    for (let i = 1; i <= num; i++) {
        if (i % 3 === 0 && i % 5 === 0) {
            output.push('FizzBuzz');
        } else if (i % 3 === 0) {
            output.push('Fizz');
        } else if (i % 5 === 0) {
            output.push('Buzz');

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/* Write a function (createCounter). It should accept an intitial integer (init).
    It should return an object with three functions.
    The three functions are:
    -- increment() increases the current value by 1 and then returns it
    -- decrement() reduces the current value by 1 and then returns it
    -- reset() sets the current value to (init) and then returns it.
    */


    const createCounter = function(init) {

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const phoneRegEx = /(?:(?<international>\+1)[ -])?\(?(?<areacode>\d{3})\)?[ -]?(?<prefix>\d{3})[ -]?(?<line_number>\d{4})/

// 1234567890
// 123-456-7890
// 123 456 7890
// (123) 456 7890
// +1 123 456 7890

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/* Top 5 most popular 


5: What is the difference between GET and POST when making an AJAX request?

    GET and POST are two different HTTP requests
        Use GET when retrieving data from the server
    Use POST when sending data from the client to the server to create/update a resource

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const str = 'abbccccddd';

function maxChar(str) {
    let charMap = {};
    let max = 0;
    let char = '';

    for (char of str) {
        charMap[char] = ++charMap[char] || 1

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function chunk(array, size) {
    return array.reduce((acc, val, i) => {
        if (i % size === 0) {
            acc.push([]);
            console.log(acc);
            console.log(i);
        }
        console.log(val);
        acc[acc.length - 1].push(val);
        return acc;

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const str = 'coding money';
const str2 = 'money coding';

const str3 = 'RAIL! SAFETY!';
const str4 = 'fairy tales';

function anagram(str1, str2) {
    const str1Arr = str1.toLowerCase().replace(/[\W]/g,'').split('').sort();
    console.log(str1Arr);
    const str2Arr = str2.toLowerCase().replace(/[\W]/g,'').split('').sort();