You can see examples in the pictures and more demo codes in the rest of post.

Type Inference

ConstructorParameters<T>

Syntax

Examples

InstanceType<T>

Syntax

Examples

ReturnType<T>

Syntax

Examples

Parameters<T>

Syntax

Examples

NonNullable<T>

Syntax

Examples

Extract<T, U>

Syntax

Examples

Exclude<T, U>

Syntax

Examples

Demo 1

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Demo 1

Demo 2

I just want to create some demo for enum to create a builder . I improved this concept step by step in demos. Notice that all the codes are doing same job but in a different way.

Demo 1

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Type Aliases, Union Types, Literal Types, Index Signature

You can find different usages of Type Aliases in the following demo code.

Type Aliases is defined with type word.

Union Types is defined with the | character to separate the different possible types.

Literal Types can be string, number or boolean

type SelectedEvent = "Click"; // string literal type

const buttonEvent: SelectedEvent = "Click";

type Color = "Red" | "Green" | "Blue"; // string literal type with union type

const buttonForeColor: Color = "Red";

type num = 1 | 3 | 5 | 7 | 9; // number literal type with union type

type bool = true | false; // boolean literal type with union type

type TRUE = true;

type FALSE = false;

Index Signature is defined as below

type Dictionary = {
    [index: string]: any;
};

const person: Dictionary = {
    "firstName": "Kenan",
    "lastName": "Hancer",
    "age": 36
};

interface StringArray {
    [index: number]: string;
}

const names: StringArray = ["Bob", "Fred"];

let name1: string = names[0];

Type Aliases can be used with Union Types and Literal Types as below

type obj = {success: true} | {success: false}; // object

type Result<T> = { success: true, value: T } | { success: false, error: string | number }; // object

type PersonCommonFields = { firstName: string, lastName: string };

type Person = PersonCommonFields & { isDeleted: true | false };

type Name = string; // simple type

type NameResolver = () => string; // function

type NameOrResolver = Name | NameResolver;

Demo1

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