Regular expressions: Difference between revisions
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| <code>\</code> || Escape character || If a character is reserved for regex, such as <code><nowiki>*</nowiki></code>, <code><nowiki>|</nowiki></code>, or <code>.</code>. Note that this is itself a reserve character, so to match for it, you need to use <code>\\</code>. || "Foo.bar apple 78.9 banana" <code><nowiki>/[A-Za-z0-9]*\.[A-Za-z0-9]*/g</nowiki></code> -> <code>[ "Foo.bar", "78.9" ]</code>
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| <code>\d</code> || Digit character class
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| <code>\D</code> || Non-digit character class
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| <code>\w</code> || Word character class
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| <code>\W</code> || Non-word character class
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| <code>\s</code> || White space character class
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| <code>\S</code> || Non-white space character class
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| <code>\t</code> || Horizontal tab
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| <code>\n</code> ||
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| <code>\r</code> || Carriage return
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| <code>\v</code> || Vertical tab
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| <code>\f</code> || Form feed
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| <code>[\b]</code> || Backspace
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| <code>\0</code> || NUL
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| <code>\u{YYYY}</code> or <code>\u{YYYY}</code> || rowspan="2" | Unicode value escape || When the <code>u</code> flag is applied. Here <code>Y</code> represents a hexadecimal number.
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| <code>\uYYYY</code> || Matches provided UTF-16 hexadecimal value. Represented with <code>Y</code>s here.
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| <code>\p{x}</code> or <code>\P{x}</code> || Unicode character class
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| <code>\cx</code> || Caret notation escape || Matches the sequence following <code>\c</code> with [[w:Caret notation|caret notation]]. Note that <code>x</code> represents a sequence of characters here, rather than a single one. || "a<br>b" <code><nowiki>/\cM\cJ//g</nowiki></code> -> <code><nowiki>[ "" ]</nowiki></code>
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! colspan=4 | Assertions
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| <code>^</code> || Input boundary beginning
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| <code>$</code> || Input boundary end
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| <code>\b</code> || Word boundary
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| <code>\B</code> || Non-word boundary
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| <code>x(?=y)</code> || Positive lookahead || Matches if <code>y</code> is after <code>x</code>, but doesn't include <code>y</code> in the output. || "Foo Bar" <code>/Foo(?= Bar)/</code> -> <code>[ "Foo" ]</code>
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| <code>x(?!y)</code> || Negative lookahead || Matches if <code>y</code> is not after <code>x</code>, but doesn't include <code>y</code> in the output. || "Foo Bar" <code>/Foo(?! Car)/</code> -> <code>[ "Foo" ]</code>
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| <code>(?<=x)y</code> || Positive lookbehind || Matches if <code>y</code> is before <code>x</code>, but doesn't include <code>y</code> in the output. || "Foo Bar" <code>/(?<=Foo )Bar/</code> -> <code>[ "Bar" ]</code>
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| <code>(?<!x)y</code> || Negative lookbehind || Matches if <code>y</code> is before <code>x</code>, but doesn't include <code>y</code> in the output. || "Foo Bar" <code>/(?<!Moo )Bar/</code> -> <code>[ "Bar" ]</code>
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! Quantifiers
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| <code>x*</code> || Wild-amount || Matches <code>x</code> any number of times, including 0. || "Foo Foo Foo Bar" <code>/(?:Foo )*Bar/g</code> -> <code>[ "Foo Foo Foo Bar" ]</code>
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| <code>x+</code> || Wild-1-or-more || Matches <code>x</code> if it occurs 1 or more times. || "Foo Bar Bar" <code>/(Foo)+ (Bar)+/</code> -> <code>[ "Foo Bar Bar" ]</code>
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| <code>x?</code> || Can occur || Matches <code>x</code> if it occurs, otherwise, ignore it. || "Foo " <code>/Foo (Bar)?/</code> -> <code>[ "Foo " ]</code>
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| <code>x{Y}</code> || Occurs set times || Matches if <code>x</code> occurs <code>Y</code> times. || "Foo Bar Bar" <code>/Fo{2} (?:Bar\s?){2}/</code> <code>[ "Foo Bar Bar" ]</code>
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| <code>x{Y,Z}</code> || Occurs between set times || Matches if <code>x</code> occurs <code>Y</code> and <code>Z</code> times. || "Foooo Bar Bar Bar Bar Bar" <code>/Fo{2,5} (?:Bar\s?){1,10}/</code> <code>[ "Foooo Bar Bar Bar Bar Bar" ]</code>
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| <code>x*?</code>, <code>x+?</code>, <code>x??</code>, <code>x{Y}?</code>, or <code>x{Y,Z}?</code> || Lazy match || Matches <code>x</code> the least number of times possible, in accordance to the base rule. || "Foooo Bar Bar Bar Bar Bar" <code>/Fo{2,5} (?:Bar\s?){1,10}?/</code> <code>[ "Foooo Bar" ]</code>
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