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JavaScript: Check whether a passed string is palindrome or not

JavaScript Function: Exercise-2 with Solution

Write a JavaScript function that checks whether a passed string is palindrome or not?

Note: A palindrome is word, phrase, or sequence that reads the same backward as forward, e.g., madam or nurses run.

Pictorial Presentation:

JavaScript: Check whether a passed string is palindrome or not

Sample Solution: -

HTML Code:

<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8/>
<title>A passed string is palindrome or not;/title>
</head>
<body>
  
</body>
</html>

JavaScript Code:

// Write a JavaScript function that checks whether a passed string is palindrome or not? 

function check_Palindrome(str_entry){
// Change the string into lower case and remove  all non-alphanumeric characters
   var cstr = str_entry.toLowerCase().replace(/[^a-zA-Z0-9]+/g,'');
	var ccount = 0;
// Check whether the string is empty or not
	if(cstr==="") {
		console.log("Nothing found!");
		return false;
	}
// Check if the length of the string is even or odd 
	if ((cstr.length) % 2 === 0) {
		ccount = (cstr.length) / 2;
	} else {
// If the length of the string is 1 then it becomes a palindrome
		if (cstr.length === 1) {
			console.log("Entry is a palindrome.");
			return true;
		} else {
// If the length of the string is odd ignore middle character
			ccount = (cstr.length - 1) / 2;
		}
	}
// Loop through to check the first character to the last character and then move next
	for (var x = 0; x < ccount; x++) {
// Compare characters and drop them if they do not match 
		if (cstr[x] != cstr.slice(-1-x)[0]) {
			console.log("Entry is not a palindrome.");
			return false;
		}
	}
	console.log("The entry is a palindrome.");
	return true;
}
check_Palindrome('madam');
check_Palindrome('nurses run');
check_Palindrome('fox');

Sample Output:

The entry is a palindrome.
The entry is a palindrome.
Entry is not a palindrome.

Flowchart:

Flowchart: JavaScript function: Check whether a passed string is palindrome or not

Live Demo:

See the Pen JavaScript -Check whether a passed string is palindrome or not-function-ex- 2 by w3resource (@w3resource) on CodePen.


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Next: Write a JavaScript function that generates all combinations of a string.

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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