What does js regular expression include?

js regular expressions include \d, \D, \w, \W, \s, \S, *, ,?, {n}, {n,}, {n,m}, ^ , $, \b, (), |, (?:), ., \, [], [^], (?=) and (?!), etc. In practical applications, these characters and metacharacters can be used to build suitable regular expressions according to specific needs. At the same time, writing regular expressions also requires certain experience and skills, and requires continuous learning and practice to master.

The operating system of this tutorial: windows10 system, javascript2023 version, DELL G3 computer.

JavaScript regular expressions are a powerful text processing tool used to match, replace, and extract specific patterns in strings. It consists of a series of characters and metacharacters that can be used to describe the pattern of a string. The following are some commonly used JavaScript regular expression characters and metacharacters:

Character category:

\d: matches any numeric character, equivalent to [0- 9].

\D: Matches any non-numeric character, equivalent to [^0-9].

\w: Matches any letter, number or underscore character, equivalent to [a-zA-Z0-9_].

\W: Matches any non-letter, number or underscore character, equivalent to [^a-zA-Z0-9_].

\s: Matches any whitespace character, including spaces, tabs, newlines, etc.

\S: Matches any non-whitespace character.

Quantifier:

*: Matches the previous element zero or more times.

: Matches the previous element one or more times.

?: Matches the previous element zero or one time.

{n}: Match the previous element exactly n times.

{n,}: Match the previous element at least n times.

{n,m}: Match the previous element at least n times and at most m times.

Boundary matching:

^: Matches the beginning of the string.

$: Matches the end of the string.

\b: Match word boundaries.

Grouping and capturing:

(): Treat the expression within parentheses as a group.

|: Matches one of two or more expressions.

(?:): Non-capturing grouping, matching results will not be saved.

Special characters:

.: Matches any character except newline.

\: escape character, used to match the special character itself.

Others:

[]: Character set, matching any character within brackets.

[^]: Negative character set, matching any character not within brackets.

(?=): Positive positive lookup, matching positions that satisfy the expression in brackets, but does not consume characters.

(?!): Forward negative preview, matching positions that do not satisfy the expression in brackets, but does not consume characters.

The above are just some of the commonly used characters and metacharacters in JavaScript regular expressions, and there are more complex usages and features. In practical applications, these characters and metacharacters can be used to build suitable regular expressions according to specific needs. At the same time, writing regular expressions also requires certain experience and skills, and requires continuous learning and practice to master.

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