This is a typing construct in Typescript (2.1+) which allows static typing for dynamically named properties. Basically, the new type will be a union of all available key properties in an object.
Questions tagged [keyof]
141 questions
1
vote
1 answer
problem NestedKeyof type with circularly references objects
So I am buildining a library and trying to implement NestedKeyof
And I found this.
type NestedKeyOf = {
[Key in keyof T & (string | number)]: T[Key] extends object
? `${Key}` | `${Key}.${NestedKeyOf}`
: `${Key}`
}[keyof…
Alen.Toma
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1
vote
1 answer
TypeScript Autocomplete Nested Input Object Key on Nested Return Object
I'm trying to create a factory that takes in a config and returns an object with some autocomplete ability. The functionality is there, but I'm stuck on getting a proper type autocompletion on part of the return value.
This is effectively what I'm…
forgo
- 932
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1 answer
TS: object type where every possible value must be taken
Given
const domain: string[] = ["A", "B", "C"];
how can I declare an object type with keys from domain and values covering whole domain?
Some examples for clarification:
const obj1 = { // correct type: values { "B", "C", "A" } of obj1 are…
DonFuchs
- 371
- 2
- 14
1
vote
1 answer
Typescript: variable of type "keyof T" used to index T is resolved as union of T values
interface SubProps1 {
foo: boolean
bar: string
baz: T
}
interface SubProps2 {
fooz: boolean
barr: string
bazd: Array
}
interface Props {
sub1: SubProps1
sub2: SubProps2
}
type CSSObjectWithLabel =…
Wilfried Sugniaux
- 13
- 3
1
vote
1 answer
How to verify that indexed type extends string?
let's say I have function func with 2 generic arguments
const func = () => {};
and a type
interface Form {
a: boolean;
b: string;
}
then I can invoke them like so without any errors
func
Andrius Juškevičius
- 23
- 5
1
vote
1 answer
How to convert TypeScript Enum key to value and value to key
Context
lets say I have the following enum with string values:
enum Fruit {
Apple = "apple",
Orange = "orange",
Banana = "banana",
Pear = "pear"
}
the user always inputs the literal string value ("apple", "banana", "orange", "pear") lets…
SagarScript
- 1,145
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vote
2 answers
In Typescript, how can I pass an array of (keyof Object) without having to hardcode it every time? How on earth can this be so complicated?
So I have the following very simple User interface and getUserById() method that retrieves a type-safe user that includes only the specified fields/properties (what is usually called a projection):
interface User {
_id: string,
username:…
cprcrack
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1 answer
it is possible to use keyof to update object in typescript?
i want to implementation a function to update object like this.
interface Object {
name: string
age: number
}
let obj = {}
function updateObject(key: keyof Object, value: ???) {
obj[key] = value;
}
It is possible in typescript? and what…
Terriermon
- 71
- 6
1
vote
1 answer
How to create a type derived from an union type in typescript
I have the following type
type DataTableCol = {
title: string;
key: K;
render?: (value: T[K]) => ReactElement;
};
I need to create another type, DataTableRow, derived from it. From type MyData = { name: string; value:…
Victor Mamede
- 25
- 4
1
vote
1 answer
How to return a specific type of object property in TypeScript?
Lets say I have a list of flags in an object as below:
type Flags = {
flag1: string,
flag2: string,
flag3: boolean,
flag4: number
}
// const myFlags: Flags = {
// flag1: 'value 1',
// flag2: 'value 1',
// flag3: true,
// flag4:…
Shnd
- 1,846
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1
vote
1 answer
How to change the interface key: value: string to [{ [key: string]: string }
I have interface
IUser {
name: string;
surname: string;
cityLocation: string;
}
the value will be
const user: IUser = {
"name": "John";
"surname": "Smith";
"cityLocation": "LA";
}
I have adapter, they have method which receive
function…
Jackson
- 884
- 2
- 13
- 22
1
vote
1 answer
Get type for dynamic field in generic (TypeScript)
Currently I have the following setup.
When I pass foo as Column.key, I want the type of the argument value for Column.formatter to be string. For bar it should be number.
As is; Typescript expects the type to be all possible types on T. So string or…
yluijten
- 123
- 2
- 8
1
vote
1 answer
Generate union type of all keys from an object with const assertion
I have an object like this (demo in ts playground):
const sites = {
stack: {url: 'https://stackoverflow.com/'},
google: {url: 'https://www.google.com/'},
azure: {url: 'https://portal.azure.com/'}
} as const
What I'd like to do is create…
KyleMit
- 30,350
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0 answers
how to declare a type that extend a abstract class which has method return type include keyof this in typescript
abstract class AbstractCard {
foo = 1
getKeys(): Array {
return ['foo']
}
}
class Card extends AbstractCard {
bar = 2
getKeys(): Array {
return [...super.getKeys(), 'bar']
}
}
const logCard = (card:…
Rmaiy
- 11
- 3
1
vote
1 answer
Conditionally getting the type of interface property in typescript
Here is my interface:
interface Responses {
200:{
foo:number;
};
204:{
bar:number;
};
}
I can get any of the property type as follow:
type TypeFor200 = Responses['200'];
However I would like to make it conditional so that if 200…
cyrus-d
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