Regular Expression Example

let myStr = "Hello World!"
let myRegex = /Hello/
myRegex.test(myStr) // true

let myRegex2 = /hello/ 
myRegex2.test(myStr) // false

let myRegex3 = /hello/i 
myRegex3.test(myStr) // true

myStr.match(myRegex) // "Hello"
let myStr2 = "Hello World! hello"
let myRegex4 = /Hello/ig
myStr2.match(myRegex4) // ["Hello,"hello"]

Match Anything with Wildcard Period

let humStr = "I'll hum a song";
let hugStr = "Bear hug";
let huRegex = /hu./;
huRegex.test(humStr); // true
huRegex.test(hugStr); // true

Match Single Character with Multiple Possibilities

let bigStr = "big";
let bagStr = "bag";
let bugStr = "bug";
let bogStr = "bog";
let bgRegex = /b[aiu]g/;
bigStr.match(bgRegex); // ["big"]
bagStr.match(bgRegex); // ["bag"]
bugStr.match(bgRegex); // ["buig"]
bogStr.match(bgRegex); // null

let quoteSample = "Beware of bugs in the above code; I have only proved it correct, not tried it.";
let vowelRegex = /[aeiou]/ig;
let result = quoteSample.match(vowelRegex);
// [ 'e',  'a',  'e',  'o',  'u',  'i',  'e',  'a',  'o',  'e',  'o',  'e',  'I',  'a',  'e',  'o',  'o',  'e',  'i',  'o',  'e',  'o',  'i',  'e',  'i' ]

Match Letters of the Alphabet

let catStr = "cat";
let batStr = "bat";
let matStr = "mat";
let bgRegex = /[a-e]at/;
catStr.match(bgRegex); //["cat"]
batStr.match(bgRegex); //["bat"]
matStr.match(bgRegex); //null

let quoteSample = "The quick brown fox jumps over the lazy dog.";
let alphabetRegex = /[a-z]/ig;
let result = quoteSample.match(alphabetRegex);//[ 'T',  'h',  'e', ... ,'d', 'o',  'g' ]

Match Numbers and Letters of the Alphabet

let jennyStr = "Jenny8675309";
let myRegex = /[a-z0-9]/ig;
jennyStr.match(myRegex);

let quoteSample = "Blueberry 3.141592653s are delicious.";
let myRegex = /[h-s2-6]/ig;
let result = quoteSample.match(myRegex);

Match Single Characters Not Specified

let quoteSample = "3 blind mice.";
let myRegex = /[^aeiou0-9]/ig;
let result = quoteSample.match(myRegex);

Match Characters that Occur One or More Times

let difficultSpelling = "Mississippi";
let myRegex = /s+/g;
let result = difficultSpelling.match(myRegex);
//[ 'ss', 'ss' ]

Match Characters that Occur Zero or More Times

let chewieQuote = "Aaaaaaaaaaaaaaaarrrgh!"
let chewieRegex = /Aa*/;
let result = chewieQuote.match(chewieRegex); // ['Aaaaaaaaaaaaaaaa']