(type1 | type2 | type3 | ........ | type-n)

let value: number|string;
value = 120;
console.log("The Numeric value of a value is: "+value);
value = "Welcome to JavaTpoint";
console.log("The String value of a value is: "+value);

The Numeric value of the value is: 120
The String value of the value is: Welcome to JavaTpoint

function display(value: (number | string))
{
    if(typeof(value) === "number")
        console.log('The given value is of type number.');
    else if(typeof(value) === "string")
        console.log('The given value is of type string.');
}
display(123);
display("ABC");

The given value is of type number.
The given value is of type of string.

let arrType:number[]|string[]; 
let i:number; 
arrType = [1,2,3,4];
console.log("Numeric type array:")  

for(i = 0;i<arrType.length;i++)
{ 
    console.log(arrType[i]); 
}

arrType = ["India","America","England"]; 
console.log("String type array:")  

for(i = 0;i<arrType.length;i++)
{ 
    console.log(arrType[i]); 
}

Numeric type array:
1
2
3
4
String type array:
India
America
England

export enum Color {RED, BLUE, WHITE}

export type Color = 'red' | 'white' | 'blue';
const myColor: Color = 'red';
console.log(myColor.toUpperCase());

RED