[Regular Expressions] Find Repeated Patterns

Posted 2020-06-12

Regular Expression Quantifiers allow us to identify a repeating sequence of characters of minimum and maximum lengths. In this lesson we‘ll use Regular Expression Quantifiers to match repeated patterns, common Quantifier patterns, and using shorthand for those common Quantifier patterns.

 

var str = `aaaaaaa`;
var regex = /a{3,}/g  // 3 to infinite
var regex = /a{3,5}/g  // 5 max, 3 min
var regex = /a{0,}/g  // {0}match the empty string, the same as a*
var regex = /a*/g
var regex = /a+/g  //at least one a
var regex = /a{0,1}/g // 0 one 1 instance should match, the same as a? 
var regex = /a?/g


var str = `
http://egghead.io
not a website
https://www.egghead.io
`;

var regex = /https{0,1}/g  // match http or https
// the same as 
var regex = /https?/g

var regex = /:\/\/.{1,}/g  //match ://anything after that
// the same as
var regex = /:\/\/.+/g

var regex = /https?:\/\/.+/g