How to check if a string character is in a JavaScript array?

Question

I'm trying to make a JavaScript function that tells how many times a vowel was repeated in a given string.

Here's what I have tried:

    function checkVowel(str) {
    vowels = ['a', 'e', 'i', 'o', 'u']
    str = "hello world"
    
    for(let i = 0; i < str.length; i++){
        if(str[i].includes(vowels)){
            console.log("worked")
        } else {
            console.log("not worked")
        }
    }
}
checkVowel()

How can I make this function check for each vowel rather than the entire array at once?

str[i].includes(vowels) => vowels.includes(str[i]). You might also want to remove the hardcoded str = "hello world"--call the function with checkVowel("hello world") instead, so you can reuse the function for different strings. — ggorlen
– ggorlen, Commented Feb 27, 2021 at 2:28
Do you want to count the number of occurrences for each vowel, or how many vowels there are in total in that string? — Thomas
– Thomas, Commented Feb 27, 2021 at 2:43

Thomas · Accepted Answer · 2021-02-27 03:34:27Z

4

Is it this what you're looking for?

function checkVowel(str) {
  const counts = Object.seal({ a: 0, e: 0, i: 0, o: 0, u: 0 });
  
  for (let char of str) {
    counts[char.toLowerCase()]++;
  }
  
  return counts;
}

console.log(checkVowel("hello world"));

edited Feb 27, 2021 at 3:34

answered Feb 27, 2021 at 2:52

Thomas

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5 Comments

DecPK Over a year ago

Perfect combination of seal and for of loop. Learned something new.

DecPK Over a year ago

But it fails if any charater is in upper case

Roarke Over a year ago

Now, I have been trying to display the number of times a vowel was repeated using string template literal but it's not working. Can you help me with that?

Thomas Over a year ago

@IshaanSharma Same game. Make a new question (don't mix multiple/different questions in one post), show what you've tried, what you got and what you expected. Even with my answer and your comment above, there's a dozen ways that you could have written this and a hundred things that could have gone wrong.

Roarke Over a year ago

Got it! Thought duplicates post aren't allowed.

DecPK · Accepted Answer · 2021-02-27 03:34:59Z

0

Another solution

function countVowel(word) {
  const vowels = ["a", "e", "i", "o", "u"];
  const wordArray = word.split("").map((s) => s.toLowerCase());
  const result = {
    a: 0,
    e: 0,
    i: 0,
    o: 0,
    u: 0
  };
  return wordArray.reduce((acc, curr) => {
    if (vowels.includes(curr)) {
      ++acc[curr];
    }
    return acc;
  }, result);
}

console.log(countVowel("Angel"));

answered Feb 27, 2021 at 3:34

DecPK

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1 Comment

Thomas Over a year ago

What's your intention? Downwards compatibility? And since you already have it: curr in result is quicker O(1) than vowels.includes(curr) O(n)

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