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regexZeroQuantifiers

Reports quantifiers with a maximum of zero, which are useless.

✅ This rule is included in the ts logical presets.

Reports quantifiers with a maximum of zero ({0} or {0,0}), which are useless because they match zero occurrences (the empty string). A quantifier with a maximum of 0 means the quantified element will never be matched, so both the quantifier and its element can be removed.

Examples

Section titled “Examples”

Simple Element with Zero Quantifier

Section titled “Simple Element with Zero Quantifier”
AEconsB0patteAE< =sp ansty="le--0:#5CA7E4;--1:#3A68">81<1/sp ansty="le--0:#5CA7E4;--1:#3A68">872{<0}sp ansty="le--0:#D9F5DD;--1:#1111">1<1/sp ansty="le--0:#D6DEEB;--1:#403F">5<3;d ivclassNa="meco">
44AEco61B0pat446<88F spans="tyle--0:#D9F5DD;--1:#11">1<111/ spans="tyle--0:#5CA7E4;--1:#3A">6<88Fa spans="tyle--0:#7FDBCA;--1:#09">61<111/ spans="tyle--0:#D6DEEB;--1:#40">3

The {0} quantifier means a will never be matched, making the entire quantified expression useless.

Zero Range Quantifier

Section titled “Zero Range Quantifier”
AEconsB0patteAE< =sp ansty="le--0:#5CA7E4;--1:#3A68">81<1/sp ansty="le--0:#5CA7E4;--1:#3A68">872{0,<0}sp ansty="le--0:#D9F5DD;--1:#1111">1<1/sp ansty="le--0:#D6DEEB;--1:#403F">5<3;d ivclassNa="meco">
44AEco61B0pat446<88F spans="tyle--0:#D9F5DD;--1:#11">1<111/ spans="tyle--0:#5CA7E4;--1:#3A">6<88Fa spans="tyle--0:#7FDBCA;--1:#09">6E72{<0,1} spans="tyle--0:#D9F5DD;--1:#11">1<111/ spans="tyle--0:#D6DEEB;--1:#40">3<1}/>

The {0,0} quantifier also means exactly zero matches, making it equivalent to an empty match.

Group with Zero Quantifier

Section titled “Group with Zero Quantifier”
AEconsB0patteAE< =sp ansty="le--0:#5CA7E4;--1:#3A68">81<1/sp ansty="le--0:#5CA7E4;--1:#3A68">8F(a72{<0}sp ansty="le--0:#D9F5DD;--1:#1111">1<1/sp ansty="le--0:#D6DEEB;--1:#403F">5<3;d ivclassNa="meco">
44AEco61B0pat446<88F spans="tyle--0:#D9F5DD;--1:#11">1<111/ spans="tyle--0:#5CA7E4;--1:#3A">688F<(ab) spans="tyle--0:#7FDBCA;--1:#09">61<111/ spans="tyle--0:#D6DEEB;--1:#40">3<)?/>

The group (ab) with {0} will never match anything useful.

Character Class with Zero Quantifier

Section titled “Character Class with Zero Quantifier”
AEconsB0patteAE< =sp ansty="le--0:#5CA7E4;--1:#3A68">81<1/sp ansty="le--0:#82AAFF;--1:#3B61">B0[a-72{<0}sp ansty="le--0:#D9F5DD;--1:#1111">1<1/sp ansty="le--0:#D6DEEB;--1:#403F">5<3;d ivclassNa="meco">
44AEco61B0pat446<88F spans="tyle--0:#D9F5DD;--1:#11">1<111/ spans="tyle--0:#82AAFF;--1:#3B">61B0[61<111/ spans="tyle--0:#D6DEEB;--1:#40">3<]*/>

The character class [a-z] with {0} will never match any character.

Options

Section titled “Options”

This rule is not configurable.

When Not To Use It

Section titled “When Not To Use It”

There is no valid use case for a quantifier with a maximum of 0, so this rule should generally always be enabled.

Further Reading

Section titled “Further Reading”

Equivalents in Other Linters

Section titled “Equivalents in Other Linters”