Feature of ES6

JavaScript ES6 is also known as ECMAScript 2015 or ECMAScript 6.ECMAScript 2015 or ES2015 is an update to the JavaScript programming language. I provide a brief summary of some features of ES6 to start quickly in ES6.

JavaScript var:
When we declare a variable using the var keyword the scope of the variable is either global or local. If we declare a variable outside of a function, the scope of the variable is global. When we declare a variable inside a function, the scope of the variable is local. For example:
var variable_name;
Here variable_name is a global variable that is accessible by any function.

function increase() {
var variable_name= 10;
}

In this example, the variable_name variable is local to the increase() function. It cannot be accessible outside of the function.

JavaScript let:
ES6 provides a new way of declaring a variable by using the let keyword. The let keyword is similar to the var keyword, except that these variables are blocked-scope. This means they are only accessible within a particular block. For example:
let variable_name;

JavaScript const:
ES6 provides a new way of declaring a constant by using the const keyword. In ES6 const will have block scoping just like the let keyword. The value of a constant cannot change through re-assignment, and it can’t be redeclared. A constant cannot share its name with a function or a variable in the same scope. For example:
const CONSTANT_NAME = value;

JavaScript Classes:
JavaScript class is used to create an object. Keyword class is used to create a class. Class is similar to a constructor function.For example:
class Person {
constructor(name) {
this.name = name;
}
}
JavaScript Arrow Function:
ES6 arrow functions provide us the way to write a shorter syntax compared to the function expression.For example,

// function expression
let x = function(x, y) {
return x * y;
}
// function expression using arrow function
let x = (x, y) => x * y;
Default perimeter value:
When we do not provide a parameter in a function then it became an undefined value that’s why we specify default parameters to set a default value in the parameters of a function. In the ES6 version, you can pass default values in the function parameters. For example,
function say(message='Hi') {
console.log(message);
}

say(); // 'Hi'
say('Hello') // 'Hello'

JavaScript Destructuring:
The destructuring syntax makes it easier to assign values to a new variable. For example,
// before you would do something like this
const person = {
name: 'Marjia',
age: 23,
gender: 'female'

}

let name = person.name;
let age = person.age;
let gender = person.gender;

//now we do something like this
const person = {
name: 'Marjia',
age: 23,
gender: 'female'

}

let { name, age, gender } = person;