regex examples javascript
Example 1: javascript regex
//Declare Reg using slash
let reg = /abc/
//Declare using class, useful for buil a RegExp from a variable
reg = new RegExp('abc')
//Option you must know: i -> Not case sensitive, g -> match all the string
let str = 'Abc abc abc'
str.match(/abc/) //Array(1) ["abc"] match only the first and return
str.match(/abc/g) //Array(2) ["abc","abc"] match all
str.match(/abc/i) //Array(1) ["Abc"] not case sensitive
str.match(/abc/ig) //Array(3) ["Abc","abc","abc"]
//the equivalent with new RegExp is
str.match('abc', 'ig') //Array(3) ["Abc","abc","abc"]
Example 2: javascript regex reference
// Javascript Regex Reference
// /abc/ A sequence of characters
// /[abc]/ Any character from a set of characters
// /[^abc]/ Any character not in a set of characters
// /[0-9]/ Any character in a range of characters
// /x+/ One or more occurrences of the pattern x
// /x+?/ One or more occurrences, nongreedy
// /x*/ Zero or more occurrences
// /x?/ Zero or one occurrence
// /x{2,4}/ Two to four occurrences
// /(abc)/ A group
// /a|b|c/ Any one of several patterns
// /\d/ Any digit character
// /\w/ An alphanumeric character (“word character”)
// /\s/ Any whitespace character
// /./ Any character except newlines
// /\b/ A word boundary
// /^/ Start of input
// /$/ End of input
Example 3: using regex in javascript
//Adding '/' around regex
var regex = /\s/g;
//or using RegExp
var regex = new RegExp("\s", "g");
Example 4: regular expression javascript
// Tests website Regular Expression against document.location (current page url)
if (/^https\:\/\/example\.com\/$/.exec(document.location)){
console.log("Look mam, I can regex!");
}
Example 5: javascript regex match sequence
// Regular expression match sequence of characters
console.log(/abc/.test("abcde")); // true
console.log(/abc/.test("abxde")); // false
Example 6: what is regular expression in javascript
let re = /ol/,
Characters \, ., \cX, \d, \D, \f, \n, \r, \s, \S, \t, \v, \w, \W, \0, \xhh, \uhhhh, \uhhhhh, [\b]
Assertions ^, $, x(?=y), x(?!y), (?<=y)x, (?<!y)x, \b, \B
Groups (x), (?:x), (?<Name>x), x|y, [xyz], [^xyz], \Number
Quantifiers *, +, ?, x{n}, x{n,}, x{n,m}
Unicode \p{UnicodeProperty}, \P{UnicodeProperty} property escapes
let defaults = new RegExp('compiled');
defaults = { dotAll: false, flags: "", global: false, ignoreCase: false, falselastIndex: 0, multiline: false, source: "abc", sticky: false, unicode: false}