JavaScript: Reverse a number

JavaScript Function: Exercise-1 with Solution

Write a JavaScript function that reverse a number.
Sample Data and output:
Example x = 32243;
Expected Output: 34223

Pictorial Presentation:

JavaScript: Reverse a number

Sample Solution: -

HTML Code:

<!DOCTYPE html>
<meta charset=utf-8 />
<title>Reverse a number</title>

JavaScript Code:

function reverse_a_number(n)
	n = n + "";
	return n.split("").reverse().join("");

Sample Output:


Assume n = 1000.
Convert a number to a string :
Code : -> n = n + "";
Note : There are different ways to convert number to string :

  • String literal -> str = "" + num + "";
  • String constructor -> str = String(num);
  • toString -> str = num.toString();
  • String Literal simple -> str = "" + num;

The split() method is used to split a String object into an array of strings by separating the string into substrings.
Code : console.log('1000'.split(""));
Output : ["1", "0", "0", "0"]

The reverse() method is used to reverse an array in place. The first array element becomes the last and the last becomes the first.
Code : console.log(["1", "0", "0", "0"].reverse());
Output : ["0", "0", "0", "1"]

The join() method is used to join all elements of an array into a string.
Code : console.log(["1", "0", "0", "0"].reverse().join(""));
Output : "0001"


Flowchart: JavaScript function: Reverse a number

See the Pen JavaScript -Reverse a number-function-ex- 1 by w3resource (@w3resource) on CodePen.

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JavaScript: Tips of the Day

JavaScript: Implicit type coercion

function sum(a, b) {
  return a + b;

sum(1, '2');

JavaScript is a dynamically typed language: we don't specify what types certain variables are. Values can automatically be converted into another type without you knowing, which is called implicit type coercion. Coercion is converting from one type into another.

In this example, JavaScript converts the number 1 into a string, in order for the function to make sense and return a value. During the addition of a numeric type (1) and a string type ('2'), the number is treated as a string. We can concatenate strings like "Hello" + "World", so what's happening here is "1" + "2" which returns "12".

Ref: https://bit.ly/323Y0P6