[TYPESCRIPT] Annotations for arrays.

arrays.ts

const carMakers = ['ford','toyota','honda'];
const dates = [new Date(), new Date()];

const carsByMake: string[][] = [];


// Help with inference when extracting values

const car = carMakers[0];
const myCare = carMakers.pop();


// Prevent incompatible values
// carMakers.push(100); -> Type error.

// Help with 'map'
carMakers.map((car: string): string => {
    // Show methods that belong to string.
    return car.toUpperCase();
})


// Multiple types - Flexible types

// const importantDates: (string | Date)[]
const importantDates = [new Date(), '2030-10-10'];
const otherImportantDates: (Date | string)[] = []

importantDates.push('2020-10-10');
otherImportantDates.push('2020-10-10');

importantDates.push(new Date());
otherImportantDates.push(new Date());