Array methods

Learn array methods like push, pop, and map.

Array methods

To add elements to an array use push, and to remove the last element use pop. The map method applies a function to each element and returns a new array. TypeScript checks these methods by their types.

let liste: number[] = [1, 2];
liste.push(3);   // [1, 2, 3]
liste.pop();     // [1, 2]

Details of push, pop and map

push appends an element to the end and returns the new length. pop removes the last element and returns it. map creates a new array, so the original array stays unchanged. Adding a wrong-typed element gives a compile error.

let isimler: string[] = ["Ali"];
isimler.push("Ayşe");
let ikili: number[] = [1, 2, 3].map(x => x * 2);
// [2, 4, 6]

Exercise Double the numbers

Define a number[] array named sayilar with the values [1, 2, 3]. Use map to multiply each element by two and store it in a new array called ikili. Then print the ikili array.

Show example solution

let sayilar: number[] = [1, 2, 3];
let ikili: number[] = sayilar.map(x => x * 2);
console.log(ikili);

Test yourself

What does the `map` method do?
- It removes an element from the array
- It applies a function to each element and returns a new array
- It converts the array to a string
- It mutates the array in place
Show answer

It applies a function to each element and returns a new array — `map` applies a function to each element and returns a new array; the original array is untouched.

Add an element with push

let meyveler: string[] = ["elma"];
meyveler.____;

Show answer

let meyveler: string[] = ["elma"];
meyveler.push("armut");

Method behaviors

push

Appends an element to the end
pop

Removes and returns the last element
map

Transforms each element and returns a new array
x => x * 2

A doubling function for map

Next lesson: readonly arrays

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