JavaScript - RegExPatterns

Brackets are used to find a range of characters.

[abc]

Find any character between the brackets

[a-z]

Find within this range of characters

[^abc]

Find any character NOT between the brackets

[0-9]

Find any digit between the brackets

[^0-9]

Find any digit NOT between the brackets

(x|y)

Find any of the alternatives specified

MetaCharacters are characters with a special meaning.

*

Find any number of characters within the range

{x}

indicates how consecutive characters it should search within

\d

Find a digit

\s

Find a whitespace character

\b

Find a match at the beginning or at the end of a word

\uxxxx

Find the Unicode character specified by the hexadecimal number xxxx

Modifiers are characters with a special meaning.

*

Find any number of characters within the range

\i

Perform case-insensitive matching

\g

Perform a global match (find all matches rather than stopping after the first match)

\m

Perform multiline matching

Quantifiers define quantities.

n+

Matches any string that contains at least one n

n*

Matches any string that contains zero or more occurrences of n

n?

Matches any string that contains zero or one occurrences of n

// Example 1 - finds all occurrences of 'e'. Use 'i' for showing only first occurrence.
var str = "Is anyone out there?";
var patt1 = /[e]/g;
var results = str.match(patt1);
$("#demo1").html(results);

// Example 2
var str2 = "Is anyone out there?" - finds all occurrences of 'anyone';
var patt2 = /anyone/g;
var results2 = str2.match(patt2);
$("#demo2").html(results2);

// Example 3 - finds all matches for 'is' (even partials).
var str3 = "Do you know if this is all there is?";
var patt3 = /[is]/gi;
var results3 = str3.match(patt3);
$("#demo3").html(results3);

// Example 4 - finds '1234'
var str4 = "123456789";
var patt4 = /[1-4]/g;
var results4 = str4.match(patt4);
$("#demo4").html(results4);

https://www.w3schools.com/js/js_regexp.asp

http://buildregex.com/

https://www.regexbuddy.com/create.html