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JavaScript: Counts the number of vowels within a string

JavaScript Function: Exercise-7 with Solution

Write a JavaScript function that accepts a string as a parameter and counts the number of vowels within the string.

Note : As the letter 'y' can be regarded as both a vowel and a consonant, we do not count 'y' as vowel here.

Sample Data and output:
Example string: 'The quick brown fox'
Expected Output: 5

Pictorial Presentation:

JavaScript: Counts the number of vowels within a string

Sample Solution: -

HTML Code:

<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8 />
<title>Counts the number of vowels within a string</title>
</head>
<body>
  
</body>
</html>

JavaScript Code:

function vowel_count(str1)
{
  var vowel_list = 'aeiouAEIOU';
  var vcount = 0;
  
  for(var x = 0; x < str1.length ; x++)
  {
    if (vowel_list.indexOf(str1[x]) !== -1)
    {
      vcount += 1;
    }
  
  }
  return vcount;
}
console.log(vowel_count("The quick brown fox"));

Sample Output:

5

Explanation:
The indexOf() method returns the index within the calling String object of the first occurrence of the specified value, starting the search at fromIndex. Returns -1 if the value is not found.
Syntax -> str.indexOf(searchValue[, fromIndex])
Parameters :
searchValue : A string representing the value to search for.
fromIndex(Optional)-> The index at which to start the searching forwards in the string. It can be any integer.

The character(s) of the string will be counted as vowel if the condition (vowel_list.indexOf(str1[x]) !== -1) matched.

>

Flowchart:

Flowchart: JavaScript function: Counts the number of vowels within a string

Live Demo:

See the Pen JavaScript -Counts the number of vowels within a string-function-ex- 7 by w3resource (@w3resource) on CodePen.


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Next: Write a JavaScript function that accepts a number as a parameter and check the number is prime or not.

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JavaScript: Tips of the Day

How to check whether a string contains a substring in JavaScript?

ECMAScript 6 introduced String.prototype.includes:

const string = "foo";
const substring = "oo";

console.log(string.includes(substring));

includes doesn't have Internet Explorer support, though. In ECMAScript 5 or older environments, use String.prototype.indexOf, which returns -1 when a substring cannot be found:

var string = "foo";
var substring = "oo";

console.log(string.indexOf(substring) !== -1);

Ref: https://bit.ly/3fFFgZv