Arrow Functions

Arrow function expressions were introduced in ES6. These expressions are a clean and concise alternative to the traditional function syntax. The syntax for an arrow function expression does not require the function keyword and uses a fat arrow => to separate the parameter(s) from the body. However, they are limited and can’t be used in all situations.

There are several variations of arrow functions:

• Arrow functions with a single parameter do not require () around the parameter list.
• Arrow functions with a single expression can use the concise function body which returns the result of the expression without the return keyword.

Syntax

Arrow function with no arguments:

const printHello = () => {
  console.log('hello');
};

printHello();
// Output: hello

Arrow functions with a single argument:

const checkWeight = (weight) => {
  console.log(`Baggage weight: ${weight} kilograms.`);
};

checkWeight(25);
// Output: Baggage weight: 25 kilograms.

Arrow function with two arguments:

const sum = (firstParam, secondParam) => {
  return firstParam + secondParam;
};

console.log(sum(2, 5));
// Output: 7

Concise arrow functions:

const multiply = (a, b) => a * b;

console.log(multiply(2, 30));
// Output: 60

Limitations

• Arrow functions do not have their own bindings to this or super, and should not be used as methods.
• Arrow functions cannot be used as constructors.
• Arrow functions cannot use yield, within its body.
• Arrow functions cannot use the special arguments keyword.