Count Vowels in String in JavaScript

1// Method 1: Using for loop
2function countVowels1(str) {
3    let count = 0;
4    let vowels = 'aeiouAEIOU';
5    
6    for (let i = 0; i < str.length; i++) {
7        if (vowels.includes(str[i])) {
8            count++;
9        }
10    }
11    return count;
12}
13
14console.log("Hello World:", countVowels1("Hello World"));
15
16// Method 2: Using for...of loop
17function countVowels2(str) {
18    let count = 0;
19    let vowels = ['a', 'e', 'i', 'o', 'u'];
20    
21    for (let char of str.toLowerCase()) {
22        if (vowels.includes(char)) {
23            count++;
24        }
25    }
26    return count;
27}
28
29console.log("\nUsing for...of:", countVowels2("JavaScript"));
30
31// Method 3: Using filter
32function countVowels3(str) {
33    let vowels = ['a', 'e', 'i', 'o', 'u'];
34    return str.toLowerCase()
35               .split('')
36               .filter(char => vowels.includes(char))
37               .length;
38}
39
40console.log("Using filter:", countVowels3("Programming"));
41
42// Method 4: Using match with regex
43function countVowels4(str) {
44    let matches = str.match(/[aeiou]/gi);
45    return matches ? matches.length : 0;
46}
47
48console.log("\nUsing regex:", countVowels4("Hello World"));
49
50// Method 5: Using reduce
51function countVowels5(str) {
52    let vowels = ['a', 'e', 'i', 'o', 'u'];
53    return str.toLowerCase()
54               .split('')
55               .reduce((count, char) => {
56                   return vowels.includes(char) ? count + 1 : count;
57               }, 0);
58}
59
60console.log("Using reduce:", countVowels5("Education"));
61
62// Method 6: Count each vowel separately
63function countEachVowel(str) {
64    str = str.toLowerCase();
65    return {
66        a: (str.match(/a/g) || []).length,
67        e: (str.match(/e/g) || []).length,
68        i: (str.match(/i/g) || []).length,
69        o: (str.match(/o/g) || []).length,
70        u: (str.match(/u/g) || []).length
71    };
72}
73
74console.log("\nEach vowel count:", countEachVowel("Hello World"));