Easy way to learn Javascript

3 min readMay 5, 2021

JavaScript is a programming language that use to create dynamic web pages. It is lightweight and most commonly used as a part of web pages. Basically, javascript is more popular for its simplicity and powerful skills.

Types of Javascript

1. Number.NaN

It represents Not A Number. It can be used to find whether a value is a number or not. Let’s see an example to make it more clear:

const isNumber =(a)=> {
  if (isNaN(a)) {
    return Number.NaN;
  }
  return a;
}

2. Number.parseFloat()

In this method, we can parse an argument and get a floating-point number. If a number can’t be parsed then it will return NaN.

Input:
const num1 = parseFloat("10.15");
const num2 = parseFloat("hello world");console.log(num1);
console.log(num2);Output:
10.15
NaN

3. Number.parseInt()

This method parses an argument and gets an integer-point number. If a number can’t be parsed then it will return NaN.

Input:
const num1 = parseInt("10.15");
const num2 = parseInt("hello world");console.log(num1);
console.log(num2);Output:
10
NaN

4. String.prototype.charAt()

charAt() method returns a specific index of character in a string.

Input:
const myFunction = () =>{
  const str = "HELLO WORLD";
  const result1 = str.charAt(0);
  const result2 = str.charAt(4);
  console.log(result1);
  console.log(result2);
}
myFunction();Output:
H
O

5. String.prototype.concat()

concat() method joins two or more strings and returns a new string.

Input:
const myFunction = () =>{
  const str1 = "HELLO ";
  const str2 ="WORLD";
  const result = str1.concat(str2);
  console.log(result);
}
myFunction();Output:
HELLO WORLD

6. String.prototype.indexOf()

indexOf() method returns the index of the first occurrence of a specified value in a string. From the search, if it can’t find any value then return -1.

Input:
const myFunction = () =>{
  const str = "Javascript is a programming language";
  const result = str.indexOf("programming");
  console.log(result);
}
myFunction();Output:
16

7. String.prototype.replace()

replace() method search a string and replace it with a specific string and returns a new string.

Input:
const myFunction = () =>{
  const str = "Javascript is a programming language.";
  const result = str.replace("Javascript","Python");
  console.log(result);
}
myFunction();Output:
Python is a programming language.

8. Array.prototype.concat()

concat() method join or merge two or more array and return a new array.

Input:
const myFunction = () =>{
  const list1= [Sabbir, Asif, Herry ];
  const list2= [Sajib, Pallab, Shuvro];
  const result = list1.concat(list2);
  console.log(result);
}
myFunction();Output:
[Sabbir, Asif, Herry, Sajib, Pallab, Shuvro]

9. Array.prototype.find()

find() method returns the first value of an array element that satisfied a given condition.

Input:const friendsAge = [10,14,17,22,35,40];
const myFunction = () =>{
  const result= friendsAge.find(age => age > 15);
  console.log(result);
}
myFunction();Output:
17

10. Array.prototype.map()

map() method calls every element of an array and returns a new array. This method will not execute if there is no value in the array.

Input:const values= [5, 10, 15, 30, 50];
const myFunction = () =>{
  const result= values.map(value => value + 10);
  console.log(result);
}
myFunction();Output:
[15, 20, 25, 40, 60]