Typescript

Question 1

What is the Template Literal Type Syntax?

Answer 1

type attrs = “Phone” | “Name”;

type target = get${attrs};

// ✅ Result
// target = "getPhone" | "getName";

Question 2

Is valid to the next in TS?

type CustomObject = {
foo: string
}

type target = get${CustomObject}

Answer 2

No, is invalid because TS do not support objects types in string Template Literal Type Syntax.

Question 3

Which types could we use in Template Literal Types Syntax?

Answer 3

Only subsets of primitives like string, number, bigint, boolean, null, undefined or a union combination of those

Question 4

What are the String Manipulation Utilities on TS?

Answer 4

Uppercase: will transform the string literal to uppercase.
Lowercase: will transform the string literal to lower.
Capitalize: will uppercase the first letter.
Uncapitalize: will lowercase the first letter.

Question 5

What the infer keyword does?

Answer 5

This keyword allows us to deduce a Type from another within a conditional Type.

type Direction = ‘left’ | ‘right’ | ‘top’ | ‘bottom’;

type InferRoot = T extends ${infer K}${Capitalize} ? K : T;

// ✅ Result1 is 'margin'
type Result1 = InferRoot;

// ✅ Result2 is 'padding'
type Result2 = InferRoot;