Exclude property from type

Question

I d like to exclude a single property from the type  How can I do that  For example I have interface XYZ     x  number    y  number    z  number     And I want to exclude property z to get type XY     x  number  y  number

User · Answer

If you prefer to use a library  use ts-essentials   import   Omit   from  ts-essentials    type ComplexObject       simple  number    nested        a  string      array     bar  number              type SimplifiedComplexObject   Omit lt ComplexObject   nested  gt       Result           simple  number          if you want to Omit multiple properties just use union type  type SimplifiedComplexObject   Omit lt ComplexObject   nested     simple  gt       Result          empty type    PS  You will find lots of other useful stuff there

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With typescript 2 8  you can use the new built-in Exclude type  The 2 8 release notes actually mention this in the section  Predefined conditional types       Note  The Exclude type is a proper implementation of the Diff type   suggested here        We did not include the Omit type because   it is trivially written as Pick lt T  Exclude lt keyof T  K gt  gt     Applying this to your example  type XY could be defined as   type XY   Pick lt XYZ  Exclude lt keyof XYZ   z  gt  gt

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I do like that   interface XYZ     x  number    y  number    z  number    const a XYZ    x 1  y 2  z 3   const   x  y     last     a  const   z     firstTwo    a  console log firstTwo  last

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Omit single property type T1   Omit lt XYZ   quot z quot  gt       x  number  y  number     multiple properties type T2   Omit lt XYZ   quot y quot     quot z quot  gt       x  number      properties conditionally e g  all string types  type Keys StringExcluded lt T gt          K in keyof T   T K  extends string   never   K   keyof T   type XYZ     x  number  y  string  z  number    type T3a   Pick lt XYZ  Keys StringExcluded lt XYZ gt  gt       x  number  z  number     Shorter version with TS 4 1 key remapping   as clause in mapped types  PR   type T3b      K in keyof XYZ as XYZ K  extends string   never   K   XYZ K          x  number  z  number     properties by string pattern e g  exclude getters  props with  get  string prefixes  type OmitGet lt T gt      K in keyof T as K extends  get  infer       never   K   T K    type XYZ2     getA  number  b  string  getC  boolean    type T4   OmitGet lt XYZ2 gt        b  string     Note  Above template literal types are supported with TS 4 1  Note 2  You can also write get  string  instead of get  infer    here   Pick  Omit and other utility types How to Pick and rename certain keys using Typescript   rename instead of exclude  Playground

User · Answer

I ve found solution with declaring some variables and using spread operator to infer type   interface XYZ     x  number    y  number    z  number     declare var   z     xy    XYZ   type XY   typeof xy       x  number  y  number      It works  but I would be glad to see a better solution

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For versions of TypeScript at or above 3 5  In TypeScript 3 5  the Omit type was added to the standard library  See examples below for how to use it   For versions of TypeScript below 3 5  In TypeScript 2 8  the Exclude type was added to the standard library  which allows an omission type to be written simply as   type Omit lt T  K extends keyof T gt    Pick lt T  Exclude lt keyof T  K gt  gt    For versions of TypeScript below 2 8  You cannot use the Exclude type in versions below 2 8  but you can create a replacement for it in order to use the same sort of definition as above  However  this replacement will only work for string types  so it is not as powerful as Exclude      Functionally the same as Exclude  but for strings only  type Diff lt T extends string  U extends string gt       P in T   P    amp    P in U   never    amp     x  string   never    T  type Omit lt T  K extends keyof T gt    Pick lt T  Diff lt keyof T  K gt  gt      And an example of that type in use   interface Test       a  string      b  number      c  boolean        Omit a single property  type OmitA   Omit lt Test   a  gt      Equivalent to   b  number  c  boolean      Or  to omit multiple properties  type OmitAB   Omit lt Test   a   b  gt      Equivalent to   c  boolean

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In Typescript 3 5    interface TypographyProps       variant  string     fontSize  number    type TypographyPropsMinusVariant   Omit lt TypographyProps   variant  gt

User · Answer

Typescript 3 5  As of Typescript 3 5  the Omit helper will be included  TypeScript 3 5 RC - The Omit Helper Type  You can use it directly  and you should remove your own definition of the Omit helper when updating

[typescript] Exclude property from type

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