Character
Class | Definition |
|---|---|
. | any character except newline |
\w | any word character [A-Za-z0-9] |
\W | NOT word character |
\d | any digit character [0-9] |
\D | NOT digit character |
\s | any whitespace |
Quantifier
Class | Definition |
|---|---|
* | 0 or more |
+ | 1 or more |
? | 0 or 1 |
{1,} | between 1 or more |
{1, 5} | between 1 and 5 |
{3} | exactly 3 |
a+? | match as few as possible |
ab | bc |
Anchors
Class | Definition |
|---|---|
^ | beginning |
$ | end |
\b | word boundary |
\B | NOT word boundary |
Character Classes
Class | Definition |
|---|---|
[abc] | any of a, b or c |
[^abc] | NOT any of a, b or c |
[a-g] | any character between a and g |
Group
Class | Definition |
|---|---|
(abc) | group |
Lookaround
Class | Definition |
|---|---|
(?=abc) | matches a group after the main expression |
(?!abc) | specifies a group that can not match after the main expression |
(?<=abc) | matches a group before the main expression (not supported by all browsers) |
(?<!abc) | specifies a group that can not match before the main expression (not supported by all browsers) |
Flags
Class | Definition |
|---|---|
g | global |
i | case insensitive |
Regex in Javascript
String: .match()
const sentence = "This is a test sentence."
const output2 = sentence.match(reg); console.log(output2);
// expected output: ['This', 'is', 'a', 'test', 'sentence']Regex: .test()
const sentence = "This is a test sentence."
const reg = /\w+/g;
const output1 = reg.test(sentence);
console.log(output1);
// expected output: trueRegex: .exec()
const sentence =
`David - 011-1111
Alex - 022-3333
Bryan - 044-5555`;
const reg = /([A-Z][a-z].+?)\s-\s(\d{3}-\d{4})/g;
let result;
while ((result = reg.exec(sentence))) {
console.log(result[1], result[2]);
}
// expected output:
// David 011-1111
// Alex 022-3333
// Bryan 044-5555