Arrow syntax

Learn to write arrow functions and their types.

Arrow syntax

Arrow functions provide a shorter way to write functions. Write => after the parameters and specify the body. With a single expression, the return is implicit.

const topla = (a: number, b: number): number => a + b;
console.log(topla(2, 3));  // 5

Arrow functions simplify code, especially for short operations.

Arrow function with block body

When the body has multiple statements, curly braces are used and an explicit return is written. Without braces, the single expression is returned automatically.

// Single expression - implicit return
const kare = (x: number): number => x * x;
// Block body - explicit return
const detay = (x: number): number => {
  let t = x * x;
  return t;
};

Both forms are valid; choose as needed.

Exercise Write an arrow function

Define an arrow function named topla with a: number and b: number parameters and return type number. It should return a + b with implicit return. Print the result of calling topla(3, 8) with console.log.

Show example solution

const topla = (a: number, b: number): number => a + b;
console.log(topla(3, 8));

Test yourself

What does <code>(a: number, b: number): number => a + b</code> return?
- The value a + b
- undefined
- A string
- An error
Show answer

The value a + b — In a single-expression arrow function, the expression is returned automatically; the result of <code>a + b</code> is returned.

Complete the arrow function

const kare = (x: number): number => x * ____;

Show answer

const kare = (x: number): number => x * x;

Arrow syntax concepts

(a, b) => a + b

Single expression, implicit return
(a, b) => { return a + b; }

Block body, explicit return
=>

Arrow operator
Arrow function

Short function syntax

Next lesson: this with arrow

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