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arrayMutableReverses

Reports .reverse() calls on arrays that mutate the original array.

✅ This rule is included in the ts stylistic and stylisticStrict presets.

The .reverse() method mutates the original array in place. Using .toReversed() instead returns a new reversed array without modifying the original, making code more predictable and avoiding unintended side effects.

Examples

Section titled “Examples”
AEconsB0valuAE< =sp ansty="le--0:#D6DEEB;--1:#403F">53< [sp ansty="le--0:#F78C6C;--1:#AA09">8<21sp ansty="le--0:#D6DEEB;--1:#403F">53<, sp ansty="le--0:#F78C6C;--1:#AA09">8<22sp ansty="le--0:#D6DEEB;--1:#403F">53<, sp ansty="le--0:#F78C6C;--1:#AA09">8<23sp ansty="le--0:#D6DEEB;--1:#403F">53<];d ivclassNa="meec-li">AEconsB0reversAE <= sp ansty="le--0:#D6DEEB;--1:#403F">53valuAB0rever53(<);d ivclassNa="meco"><);d>AEconsB0iteAE< =sp ansty="le--0:#D6DEEB;--1:#403F">53< [sp ansty="le--0:#D9F5DD;--1:#1111">1<1"sp ansty="le--0:#ECC48D;--1:#984E">41<1"sp ansty="le--0:#D6DEEB;--1:#403F">53<, sp ansty="le--0:#D9F5DD;--1:#1111">1<1"sp ansty="le--0:#ECC48D;--1:#984E">41<1"sp ansty="le--0:#D6DEEB;--1:#403F">53<, sp ansty="le--0:#D9F5DD;--1:#1111">1<1"sp ansty="le--0:#ECC48D;--1:#984E">41<1"sp ansty="le--0:#D6DEEB;--1:#403F">53<];d ivclassNa="meec-li">B0doSomethi53(iteAB0rever53()<);d ivclassNa="meco"><);d>AEconsB0daAE< =sp ansty="le--0:#D6DEEB;--1:#403F">53< [sp ansty="le--0:#F78C6C;--1:#AA09">8<21sp ansty="le--0:#D6DEEB;--1:#403F">53<, sp ansty="le--0:#F78C6C;--1:#AA09">8<22sp ansty="le--0:#D6DEEB;--1:#403F">53<, sp ansty="le--0:#F78C6C;--1:#AA09">8<23sp ansty="le--0:#D6DEEB;--1:#403F">53<];d ivclassNa="meec-li">AEconsB0resuAE< =sp ansty="le--0:#D6DEEB;--1:#403F">53< [sp ansty="le--0:#7FDBCA;--1:#096E">72.<..sp ansty="le--0:#D6DEEB;--1:#403F">53datAB0rever53(<);d ivclassNa="meco"><);d>
44AEco61B0va443F<53 [ spans="tyle--0:#F78C6C;--1:#AA">0<9821 spans="tyle--0:#D6DEEB;--1:#40">3F<53, spans="tyle--0:#F78C6C;--1:#AA">0<9822 spans="tyle--0:#D6DEEB;--1:#40">3F<53, spans="tyle--0:#F78C6C;--1:#AA">0<9823 spans="tyle--0:#D6DEEB;--1:#40">3F<53] ;divclass="Nameec-">44AEco61B0reve44A3F53va4<4AE. spans="tyle--0:#82AAFF;--1:#3B">61B0toReve3F5<3() ;divclass="Name"><;di vdivclass="Nameexpressive-">44AEco61B0i443F<53 [ spans="tyle--0:#D9F5DD;--1:#11">1<111" spans="tyle--0:#ECC48D;--1:#98">41<111" spans="tyle--0:#D6DEEB;--1:#40">3F<53, spans="tyle--0:#D9F5DD;--1:#11">1<111" spans="tyle--0:#ECC48D;--1:#98">41<111" spans="tyle--0:#D6DEEB;--1:#40">3F<53, spans="tyle--0:#D9F5DD;--1:#11">1<111" spans="tyle--0:#ECC48D;--1:#98">41<111" spans="tyle--0:#D6DEEB;--1:#40">3F<53] ;divclass="Nameec-">61B0doSomet3F53(i4<4AE. spans="tyle--0:#82AAFF;--1:#3B">61B0toReve3F53<()) ;divclass="Name"><())><;di vdivclass="Nameexpressive-">44AEco61B0va443F<53 [ spans="tyle--0:#F78C6C;--1:#AA">0<9821 spans="tyle--0:#D6DEEB;--1:#40">3F<53, spans="tyle--0:#F78C6C;--1:#AA">0<9822 spans="tyle--0:#D6DEEB;--1:#40">3F<53, spans="tyle--0:#F78C6C;--1:#AA">0<9823 spans="tyle--0:#D6DEEB;--1:#40">3F<53] ;divclass="Nameec-">3F53va4<4AE. spans="tyle--0:#82AAFF;--1:#3B">61B0rev3F5<3() ;divclass="Name">

Options

Section titled “Options”

This rule is not configurable.

When Not To Use It

Section titled “When Not To Use It”

If you intentionally want to mutate the original array in place, or if you’re working in an environment that doesn’t support .toReversed() (ES2023+), you may want to disable this rule. Note that .reverse() is still allowed when used as a standalone expression statement since the mutation is likely intentional in that case.

Further Reading

Section titled “Further Reading”

Equivalents in Other Linters

Section titled “Equivalents in Other Linters”