JavaScript Arrow Functions

In this tutorial, you will learn about JavaScript arrow function with the help of examples.

Arrow function is one of the features introduced in the ES6 version of JavaScript. It allows you to create functions in a cleaner way compared to regular functions. For example,

This function

// function expression
let x = function(x, y) {
   return x * y;
}

can be written as

// using arrow functions
let x = (x, y) => x * y;

using an arrow function.

Arrow Function Syntax

The syntax of the arrow function is:

let myFunction = (arg1, arg2, ...argN) => {
    statement(s)
}

Here,

• myFunction is the name of the function
• arg1, arg2, ...argN are the function arguments
• statement(s) is the function body

If the body has single statement or expression, you can write arrow function as:

let myFunction = (arg1, arg2, ...argN) => expression

Example 1: Arrow Function with No Argument

If a function doesn’t take any argument, then you should use empty parentheses. For example,

let greet = () => console.log('Hello');
greet(); // Hello

Example 2: Arrow Function with One Argument

If a function has only one argument, you can omit the parentheses. For example,

let greet = x => console.log(x);
greet('Hello'); // Hello 

Example 3: Arrow Function as an Expression

You can also dynamically create a function and use it as an expression. For example,

let age = 5;

let welcome = (age < 18) ?
  () => console.log('Baby') :
  () => console.log('Adult');

welcome(); // Baby

Example 4: Multiline Arrow Functions

If a function body has multiple statements, you need to put them inside curly brackets {}. For example,

let sum = (a, b) => {
    let result = a + b;
    return result;
}

let result1 = sum(5,7);
console.log(result1); // 12

this with Arrow Function

Inside a regular function, this keyword refers to the function where it is called.

However, this is not associated with arrow functions. Arrow function does not have its own this. So whenever you call this, it refers to its parent scope. For example,

Inside a regular function

function Person() {
    this.name = 'Jack',
    this.age = 25,
    this.sayName = function () {

        // this is accessible
        console.log(this.age);

        function innerFunc() {

            // this refers to the global object
            console.log(this.age);
            console.log(this);
        }

        innerFunc();

    }
}

let x = new Person();
x.sayName();

Output

25
undefined
Window {}

Hope this helps in improvising your JavaScript code for your Power Platform Implementations

Happy CRM’ing.

Cheers,

PMDY

Author: Pavan Mani Deep Y

Technology geek who loves sharing my leanings, quick tips and new features on Dynamics 365 & related tools, technologies. An Azure IOT Enthusiast.... View all posts by Pavan Mani Deep Y