Understanding the ECMA Script specification

ECMA SCRIPT

Javascript is a programming language for the web. There are numerous frameworks and libraries for javascript. Javascript is used in web development for both the front and back ends. A cross-platform JavaScript runtime environment is Node.js. The backend is node js.

European Computer Manufacturers Association is what ECMA Script stands for. The scripting language on which JavaScript is built is called ECMAScript. Additionally, it works with node js. A framework or library is not what an ECMA script is.

History and version of the script.

1. It First appeared in 1997, 23 years ago.

2. First edition in June 1997.

3. ES6 (6th edition) in 2015 also called ECMA Script 2015.

Feature in ES6.

1. let and const.

2 Arrow Functions

3. Multi-line Strings

4. Default Parameters

5. Template Literals

6. Destructuring Assignment

7. Template Literals

8. Promises

9. Classes

10. Modules

11. Default Parameters.

12. Find and findIndex

13. rest parameters

let and const Keywords.

let and const keywords are used when declaring a variable in javascript. let and const have to block scope when declaring a variable through the const keyword its value is constant and can not change. when declaring a variable with a let keyword can not be Redeclared, its scope has block scope. 

let a = 10;

const  b = 'oodles'

Default Parameters.

It is used in functions when we do not assign any parameters, 

for example. 

function test(a,b=1){

    return a+b;

}

console.warn(add(10))

Template Literals

it is also known as string template literals. It is used to concrete a string.

example.

let a = 'test 1'

let b = 'test2'

console.log(`First value of of ${a} and second value of ${b}`);

Find and findIndex

find method is to return the first value of an array and object. it returns undefined when the condition is not matched.

let data = [1,2,3,4]

let result = data.find(()=>{

    return item<3;

})

console.log(result);

The findIndex method returns the index of the first element. it returns -1 when the condition is not matched.

let arr = [1,2,3,4]

let result = arr.findIndex(()=>{

    return item<3;

})

console.log(result);

Arrow Function

Arrow functions were introduced in ES6.  it allows writing a function in a short method.

const a  = ()=>{

    console. log(10)

}

console.log(a);

If the function has only one statement, and the statement returns a value, you can remove the brackets and the return keyword, this statement only work if the function has only one statement.

a = () => console.log (1)

this keyword is not worked inside the arrow function.

Classes

Classes in javascript are built on prototypes. the class keyword we used to create a class. created a class method syntax similar to the object in javascript. class is introduced in es6. inheritance is also supported in classes.Classes are a unique type of function in JavaScript.

class Fruits{

            name="orange"

            constructor()

            {

                console. warn("constructor", this. name)

            }

             getFruits(item)

            {

                return item

            }

        }

        let f1= new Fruits;

        console.warn(f1.name)

Rest parameters

With the help of rest parameters, we efficiently handled parameters in a function. We often used rest parameters when we don't know how many arguments are passed.

       function fruits(a,...z)

       {

           console.warn("fruits",z)

       }

       function test()

       {

       }

       fruits('apple', 'banana', 'kiwi', 'orange', 'papaya', test);