I have an object like this:
{
"address": ["line1", "line2", "line3"]
}
How to define address in an interface? the number of elements in the array is not fixed.
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5I strongly suggest reading the documentation.user663031– user6630312017-08-20 09:23:11 +00:00Commented Aug 20, 2017 at 9:23
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7 Answers
interface Addressable {
address: string[];
}
4 Comments
Aluan Haddad
Thumbs up for a well-named interface.
krupesh Anadkat
As an extension, if you have a custom interface lets say
Customer and you need to have another parent interface which should have List then it would be like Customer[]
Ooker
@AluanHaddad can you explain more why the interface name is good?
Aluan Haddad
@Ooker because it is an adjective. It describes a capability or behavior as opposed to a lineage.
An array is a special type of data type which can store multiple values of different data types sequentially using a special syntax.
TypeScript supports arrays, similar to JavaScript. There are two ways to declare an array:
- Using square brackets. This method is similar to how you would declare arrays in JavaScript.
let fruits: string[] = ['Apple', 'Orange', 'Banana'];
- Using a generic array type, Array.
let fruits: Array<string> = ['Apple', 'Orange', 'Banana'];
Both methods produce the same output.
Of course, you can always initialize an array like shown below, but you will not get the advantage of TypeScript's type system.
let arr = [1, 3, 'Apple', 'Orange', 'Banana', true, false];
answered Feb 24, 2020 at 14:09
Husniddin Qurbonboyev
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Comments
It's simple as this:
address: string[]
Comments
This is the answer I came here for:
enum Lines {
"line1",
"line2",
"line3",
}
interface Addressable {
address: keyof typeof Lines;
}
Comments
Or:
{ address: Array<string> }
Comments
I think the best way to do it is something like:
type yourtype = { [key: string]: string[] }
1 Comment
Kim Skogsmo
This would define a type of an object with property keys as strings, each of which would hold a value of a string array, which is not what OP asked.
Here is how the cool kids do it nowadays.
export type stringArray = [string][number][];
Explanation:
[string] creates a tuple of string
[number] cast the tuple into a string
[] declares it as an array
For non believers, here is the proof:
2 Comments
Pepijn Olivier
What is better about this than just using
String[] ? (Aside from it not being as cool)
Brandon
it has nothing better than
string[] other than being less readable. but at least you learn about type casting in Typescript.