regex101: JavaScript Match Workspace

1st Alternative[\t\u000b\u000c\ufeff\p{Space_Separator}\n\r\u2028\u2029]

Character Class[\t\u000b\u000c\ufeff\p{Space_Separator}\n\r\u2028\u2029]

\ta tab character (ASCII 9)

\u000bthe literal (B₁₆ / 13₈ / 11₁₀)

\u000cthe literal (C₁₆ / 14₈ / 12₁₀)

\ufeffthe literal (FEFF₁₆ / 177377₈ / 65279₁₀)

\p{Space_Separator}a space separator with non-zero width

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

\ra carriage return (ASCII 13)

\u2028the literal   (2028₁₆ / 20050₈ / 8232₁₀)

\u2029the literal   (2029₁₆ / 20051₈ / 8233₁₀)

2nd Alternative\/\*(?:(?!\*\/)[^]*?)?\*\/

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

\*the literal * (42₁₀ / 52₈ / 2A₁₆)

Non-Capturing Group(?:(?!\*\/)[^]*?)?

?repeats the group contents below at most once:

Negative Lookahead(?!\*\/)

\*the literal * (42₁₀ / 52₈ / 2A₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

[^]*?any character, including newline, repeated any number of times

\*the literal * (42₁₀ / 52₈ / 2A₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

3rd Alternative)[^]*?)?-->

<!--the literal text <!--

Non-Capturing Group(?:(?!-->)[^]*?)?

?repeats the group contents below at most once:

Negative Lookahead(?!-->)

-->the literal text -->

[^]*?any character, including newline, repeated any number of times

-->the literal text -->

4th Alternative\/\/[^\n\r\u2028\u2029]*

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

Negated Character Class[^\n\r\u2028\u2029]*

*matches any number of characters outside the set below:

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

\ra carriage return (ASCII 13)

\u2028the literal   (2028₁₆ / 20050₈ / 8232₁₀)

\u2029the literal   (2029₁₆ / 20051₈ / 8233₁₀)

5th Alternative#?(?:[$_\p{ID_Start}]|\\(?:u[0-9a-fA-F]{4}|u\{(?:(?:10|[0-9])[0-9a-fA-F]{4}|[0-9a-fA-F]{1,5})\}))(?:[$\p{ID_Continue}]|\\(?:u[0-9a-fA-F]{4}|u\{(?:(?:10|[0-9])[0-9a-fA-F]{4}|[0-9a-fA-F]{1,5})\}))*

#?optionally matches the literal # (35₁₀ / 43₈ / 23₁₆)

Non-Capturing Group(?:[$_\p{ID_Start}]|\\(?:u[0-9a-fA-F]{4}|u\{(?:(?:10|[0-9])[0-9a-fA-F]{4}|[0-9a-fA-F]{1,5})\}))

1st Alternative[$_\p{ID_Start}]

Character Class[$_\p{ID_Start}]

$the literal $ (36₁₀ / 44₈ / 24₁₆)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

\p{ID_Start}characters for which the ID_Start binary property is true

2nd Alternative\\(?:u[0-9a-fA-F]{4}|u\{(?:(?:10|[0-9])[0-9a-fA-F]{4}|[0-9a-fA-F]{1,5})\})

\\the literal \ (92₁₀ / 134₈ / 5C₁₆)

Non-Capturing Group(?:u[0-9a-fA-F]{4}|u\{(?:(?:10|[0-9])[0-9a-fA-F]{4}|[0-9a-fA-F]{1,5})\})

1st Alternativeu[0-9a-fA-F]{4}

uthe literal u (117₁₀ / 165₈ / 75₁₆) (case sensitive)

Character Class[0-9a-fA-F]{4}

{4}matches exactly 4 characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

a-fone character from a (97₁₀) to f (102₁₀) (case sensitive)

A-Fone character from A (65₁₀) to F (70₁₀) (case sensitive)

2nd Alternativeu\{(?:(?:10|[0-9])[0-9a-fA-F]{4}|[0-9a-fA-F]{1,5})\}

uthe literal u (117₁₀ / 165₈ / 75₁₆) (case sensitive)

\{the literal { (123₁₀ / 173₈ / 7B₁₆)

Non-Capturing Group(?:(?:10|[0-9])[0-9a-fA-F]{4}|[0-9a-fA-F]{1,5})

1st Alternative(?:10|[0-9])[0-9a-fA-F]{4}

Non-Capturing Group(?:10|[0-9])

1st Alternative10

10the literal text 10

2nd Alternative[0-9]

Character Class[0-9]

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Character Class[0-9a-fA-F]{4}

2nd Alternative[0-9a-fA-F]{1,5}

\}the literal } (125₁₀ / 175₈ / 7D₁₆)

Non-Capturing Group(?:[$\p{ID_Continue}]|\\(?:u[0-9a-fA-F]{4}|u\{(?:(?:10|[0-9])[0-9a-fA-F]{4}|[0-9a-fA-F]{1,5})\}))*

6th Alternative(?:\?\.(?![0-9])|\{|$|$|\[|\]|;|,|~|:|\.\.\.|\.|<<=|<<|<=|<|>>>=|>>>|>>=|>>|>=|>|===|==|=>|=|!==|!=|!|\*\*=|\*\*|\*=|\*|%=|%|\+\+|\+=|\+|--|-=|-|&&=|&&|&=|&|\|\|=|\|\||\|=|\||\?\?=|\?\?|\?|\^=|\^)

7th Alternative(?:(?:0|[1-9](?:_?(?:[0-9](?:_[0-9])*)+)?|0[0-7]*[89][0-9]+)\.?(?:[0-9](?:_[0-9])*)*(?:[eE][+-]?(?:[0-9](?:_[0-9])*)+)?)

8th Alternative(?:\.(?:[0-9](?:_[0-9])*)+(?:[eE][+-]?(?:[0-9](?:_[0-9])*)+)?)

9th Alternative(?:(?:0|[1-9](?:_?(?:[0-9](?:_[0-9])*)+)?|0[0-7]*[89][0-9]+)?[eE][+-]?(?:[0-9](?:_[0-9])*)+)

10th Alternative(?:0|[1-9](?:_?(?:[0-9](?:_[0-9])*)+)?)n

11th Alternative(?:0[bB](?:[01](?:_[01])*)+|0[oO](?:[0-7](?:_[0-7])*)+|0[xX](?:[0-9a-fA-F](?:_[0-9a-fA-F])*)+)n?

12th Alternative0[0-7]+

13th Alternative(["'])(?:(?!\1)[^\\\n\r]|\\(?:['"\\bfnrtv]|[^'"\\bfnrtv0-9xu\n\r\u2028\u2029]|0(?![0-9])|0(?=[89])|[1-7](?![0-7])|[0-3][0-7]{1,2}|[4-7][0-7]|[89]|x[0-9a-fA-F]{2}|u[0-9a-fA-F]{4}|u\{(?:(?:10|[0-9])[0-9a-fA-F]{4}|[0-9a-fA-F]{1,5})\})|\\(?:\r\n|\n|\r|\u2028|\u2029))*\1

14th Alternative`(?:\$(?!\{)|\\(?:['"\\bfnrtv]|[^'"\\bfnrtv0-9xu\n\r\u2028\u2029]|0(?![0-9])|x[0-9a-fA-F]{2}|(?:u[0-9a-fA-F]{4}|u\{(?:(?:10|[0-9])[0-9a-fA-F]{4}|[0-9a-fA-F]{1,5})\}))|\\(?:0[0-9]|[1-9]|x(?![0-9a-fA-F])|x[0-9a-fA-F](?![0-9a-fA-F])|u(?![0-9a-fA-F{])|u[0-9a-fA-F]{1,3}(?![0-9a-fA-F])|u\{(?![0-9a-fA-F])|u\{(?:1[1-9a-fA-F][0-9a-fA-F]{4}|[2-9a-fA-F][0-9a-fA-F]{5}|[0-9a-fA-F]{7,})(?![0-9a-fA-F])|u\{(?:(?:10|[0-9])[0-9a-fA-F]{4}|[0-9a-fA-F]{1,5})(?![0-9a-fA-F}]))|\\(?:\r\n|\n|\r|\u2028|\u2029)|\r\n|[^`\\$])*(?:`|\$\{)

15th Alternative#![^\n\r\u2028\u2029]*

16th Alternative\/(?:[^\n\r\u2028\u2029*\\/[]|\\[^\n\r\u2028\u2029]|\[(?:[^\n\r\u2028\u2029\]\\]|\\[^\n\r\u2028\u2029])*\])(?:[^\n\r\u2028\u2029\\/[]|\\[^\n\r\u2028\u2029]|\[(?:[^\n\r\u2028\u2029\]\\]|\\[^\n\r\u2028\u2029])*\])*\/[$\p{ID_Continue}]*

Global pattern flags

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

u modifier: unicode. Enables Unicode-aware matching and escape syntax

Search reference

Regular Expression

[\t\u000b\u000c\ufeff\p{Space_Separator}\n\r\u2028\u2029]|\/\*(?:(?!\*\/)[^]*?)?\*\/|<!--(?:(?!-->)[^]*?)?-->|\/\/[^\n\r\u2028\u2029]*|#?(?:[$_\p{ID_Start}]|\\(?:u[0-9a-fA-F]{4}|u\{(?:(?:10|[0-9])[0-9a-fA-F]{4}|[0-9a-fA-F]{1,5})\}))(?:[$\p{ID_Continue}]|\\(?:u[0-9a-fA-F]{4}|u\{(?:(?:10|[0-9])[0-9a-fA-F]{4}|[0-9a-fA-F]{1,5})\}))*|(?:\?\.(?![0-9])|\{|\(|\)|\[|\]|;|,|~|:|\.\.\.|\.|<<=|<<|<=|<|>>>=|>>>|>>=|>>|>=|>|===|==|=>|=|!==|!=|!|\*\*=|\*\*|\*=|\*|%=|%|\+\+|\+=|\+|--|-=|-|&&=|&&|&=|&|\|\|=|\|\||\|=|\||\?\?=|\?\?|\?|\^=|\^)|(?:(?:0|[1-9](?:_?(?:[0-9](?:_[0-9])*)+)?|0[0-7]*[89][0-9]+)\.?(?:[0-9](?:_[0-9])*)*(?:[eE][+-]?(?:[0-9](?:_[0-9])*)+)?)|(?:\.(?:[0-9](?:_[0-9])*)+(?:[eE][+-]?(?:[0-9](?:_[0-9])*)+)?)|(?:(?:0|[1-9](?:_?(?:[0-9](?:_[0-9])*)+)?|0[0-7]*[89][0-9]+)?[eE][+-]?(?:[0-9](?:_[0-9])*)+)|(?:0|[1-9](?:_?(?:[0-9](?:_[0-9])*)+)?)n|(?:0[bB](?:[01](?:_[01])*)+|0[oO](?:[0-7](?:_[0-7])*)+|0[xX](?:[0-9a-fA-F](?:_[0-9a-fA-F])*)+)n?|0[0-7]+|(["'])(?:(?!\1)[^\\\n\r]|\\(?:['"\\bfnrtv]|[^'"\\bfnrtv0-9xu\n\r\u2028\u2029]|0(?![0-9])|0(?=[89])|[1-7](?![0-7])|[0-3][0-7]{1,2}|[4-7][0-7]|[89]|x[0-9a-fA-F]{2}|u[0-9a-fA-F]{4}|u\{(?:(?:10|[0-9])[0-9a-fA-F]{4}|[0-9a-fA-F]{1,5})\})|\\(?:\r\n|\n|\r|\u2028|\u2029))*\1|`(?:\$(?!\{)|\\(?:['"\\bfnrtv]|[^'"\\bfnrtv0-9xu\n\r\u2028\u2029]|0(?![0-9])|x[0-9a-fA-F]{2}|(?:u[0-9a-fA-F]{4}|u\{(?:(?:10|[0-9])[0-9a-fA-F]{4}|[0-9a-fA-F]{1,5})\}))|\\(?:0[0-9]|[1-9]|x(?![0-9a-fA-F])|x[0-9a-fA-F](?![0-9a-fA-F])|u(?![0-9a-fA-F{])|u[0-9a-fA-F]{1,3}(?![0-9a-fA-F])|u\{(?![0-9a-fA-F])|u\{(?:1[1-9a-fA-F][0-9a-fA-F]{4}|[2-9a-fA-F][0-9a-fA-F]{5}|[0-9a-fA-F]{7,})(?![0-9a-fA-F])|u\{(?:(?:10|[0-9])[0-9a-fA-F]{4}|[0-9a-fA-F]{1,5})(?![0-9a-fA-F}]))|\\(?:\r\n|\n|\r|\u2028|\u2029)|\r\n|[^`\\$])*(?:`|\$\{)|#![^\n\r\u2028\u2029]*|\/(?:[^\n\r\u2028\u2029*\\/[]|\\[^\n\r\u2028\u2029]|\[(?:[^\n\r\u2028\u2029\]\\]|\\[^\n\r\u2028\u2029])*\])(?:[^\n\r\u2028\u2029\\/[]|\\[^\n\r\u2028\u2029]|\[(?:[^\n\r\u2028\u2029\]\\]|\\[^\n\r\u2028\u2029])*\])*\/[$\p{ID_Continue}]*

New

const a = 5;
const b = `${a} ${a}`;

Regular Expressions 101

Regular Expression

Substitution