Regular Expressions 101

^start of line

Non-Capturing Group(?:var|const)

1st Alternativevar

varthe literal text var (case sensitive)

2nd Alternativeconst

constthe literal text const (case sensitive)

\s*any whitespace character, repeated any number of times

Group 1([a-z$_]+\s*=\s*require$('|")(?:assert|fs|path|child_process)\2$,?[\n\r\t\s]*)*

*repeats the group contents below any number of times:

Character Class[a-z$_]+

+matches at least one character from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

$the literal $ (36₁₀ / 44₈ / 24₁₆)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

\s*any whitespace character, repeated any number of times

=the literal = (61₁₀ / 75₈ / 3D₁₆)

\s*any whitespace character, repeated any number of times

requirethe literal text require (case sensitive)

\(the literal ( (40₁₀ / 50₈ / 28₁₆)

Group 2('|")

1st Alternative'

'the literal ' (39₁₀ / 47₈ / 27₁₆)

2nd Alternative"

"the literal " (34₁₀ / 42₈ / 22₁₆)

Non-Capturing Group(?:assert|fs|path|child_process)

1st Alternativeassert

assertthe literal text assert (case sensitive)

2nd Alternativefs

fsthe literal text fs (case sensitive)

3rd Alternativepath

paththe literal text path (case sensitive)

4th Alternativechild_process

child_processthe literal text child_process (case sensitive)

\2the text saved by group 2

\)the literal ) (41₁₀ / 51₈ / 29₁₆)

,?optionally matches the literal , (44₁₀ / 54₈ / 2C₁₆)

Character Class[\n\r\t\s]*

*matches any number of characters from the set below:

\na line-feed (newline) character (ASCII 10)

\ra carriage return (ASCII 13)

\ta tab character (ASCII 9)

\sany whitespace character

;the literal ; (59₁₀ / 73₈ / 3B₁₆)

$end of line

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

^(?:var|const)\s*([a-z$_]+\s*=\s*require\(('|")(?:assert|fs|path|child_process)\2\),?[\n\r\t\s]*)*;$

New

var pth = require("path");
const asrt = require('assert'),
     fs = require('fs'),
     cp = require('child_process');

Regular Expression

Substitution