Is key-value pair available in Typescript

Question

Is key value pair available in typescript  If yes how to do that  Can anyone provide sample example links

User · Answer

A concise way is to use a tuple as key-value pair:

const keyVal: [string, string] =  ["key", "value"] // explicit type
// or
const keyVal2 = ["key", "value"] as const // inferred type with const assertion

[key, value] tuples also ensure compatibility to JS built-in objects:

Object, esp. Object.entries, Object.fromEntries
Map, esp. Map.prototype.entries and new Map() constructor
Set, esp. Set.prototype.entries

You can create a generic KeyValuePair type for reusability:

type KeyValuePair<K extends string | number, V = unknown> = [K, V]
const kv: KeyValuePair<string, string> = ["key", "value"]

TS 4.0: Named tuples

Upcoming TS 4.0 provides named/labeled tuples for better documentation and tooling support:

type KeyValuePairNamed = [key: string, value: string] // add `key` and `value` labels
const [key, val]: KeyValuePairNamed = ["key", "val"] // array destructuring for convenience

Working playground example

User · Answer

class Pair lt T1  T2 gt        private key  T1      private value  T2       constructor key  T1  value  T2            this key   key          this value   value             getKey             return this key             getValue             return this value          const myPair   new Pair lt string  number gt   test   123   console log myPair getKey    myPair getValue

User · Answer

You can also consider using Record  like this   const someArray  Record lt string  string gt              first    one          second    two        Or write something like this   const someArray   key  string  value  string             key   first   value   one         key   second   value   two

User · Answer

TypeScript has Map  You can use like  public myMap   new Map lt K V gt     k1  v1    k2  v2       myMap get key      returns value myMap set key  value      import a new data myMap has key      check data

User · Answer

an example of a key value pair is   key  string   string you can put anything as the value  of course

User · Answer

Is key-value pair available in Typescript    If you think of a C  KeyValuePair lt string  string gt   No  but you can easily define one yourself   interface KeyValuePair       key  string      value  string      Usage   let foo  KeyValuePair     key   k   value   val

User · Answer

Is key-value pair available in Typescript   Yes  Called an index signature  interface Foo       key  string   Bar     let foo Foo        Here keys are string and values are Bar  More You can use an es6 Map for proper dictionaries  polyfilled by core-js

User · Answer

The simplest way would be something like   var indexedArray    key  string   number    Usage   var indexedArray    key  string   number          foo  2118      bar  2118    indexedArray  foo     2118  indexedArray foo  2118   let foo   indexedArray  myKey    let bar   indexedArray myKey

User · Answer

Another simple way is to use a tuple      Declare a tuple type let x   string  number      Initialize it x     hello   10      Access elements console log  First      x  0       Second      x  1       Output      First  hello Second  10

User · Answer

Not for the questioner  but for all others  which are interested  See  How to define Typescript Map of key value pair  where key is a number and value is an array of objects  The solution is therefore   let yourVar  Map lt YourKeyType  YourValueType gt      now you can use it  yourVar   new Map lt YourKeyType  YourValueType gt     yourVar YourKeyType     lt YourValueType gt  yourValue    Cheers

User · Answer

If you are trying to use below example Example    value1   quot value1 quot    And add conditionalData dynamically based on some condition  Try let dataToWrite  any    value1   quot value1 quot     if conditionalData     dataToWrite  quot conditionalData quot     conditionalData

[typescript] Is key-value pair available in Typescript?

TS 4.0: Named tuples

Examples related to typescript