Write a hasNoneLetters function that takes 2 strings phrase and blacklist and returns true, if phrase does not contain any letters from blacklist, otherwise returns false.

Comparison should be case-insensitive, it means x inside blacklist does not allow using X.

Examples:

hasNoneLetters('Mate Academy', 'pqrs') === true;
hasNoneLetters('ABC', 'a') === false;

my answer was:

function hasNoneLetters(phrase, blacklist) {
  if(phrase.includes(blacklist)) {
    return true;
  } else {
    return false;
  }
} 

but one test didn't passed saying 'It should return true if no matching letters' mine returned false;

CodePudding user response：

function hasNoneLetters(phrase, blacklist) {
  const r = new RegExp(`[${blacklist}]`, 'i')
  return Boolean(phrase.match(r))
}

console.log(hasNoneLetters('Mate Academy', 'pqrs'))
console.log(hasNoneLetters('ABC', 'a'))

CodePudding user response：

By checking with the includes method, you're only looking if the string passed in arguments is contains inside the other string.

For example :

Phrase	blacklist	expected return	return value
Hello	hl	false	true

while your code was working for substrings like this

Phrase	blacklist	expected return	return value
Hello	hel	true	true
World	ld	true	true

To make the program work, you need to loop through all the characters and check if those are included in the string !

Example

function hasNoneLetters(phrase, blacklist) {
  const letters = blacklist.split('')
  
  for (const letter of letters){
    if (phrase.includes(letter)) return false
  }
  
  return true
} 

console.log(hasNoneLetters("Hello world", "ab")) // true
console.log(hasNoneLetters("Hello world", "abcd")) // false

---

Note : as @albjerto mentionned, you should also check with case sensitivity.

This can be done using the toLowerCase method on the phrase and the blacklist.

Example :

function hasNoneLetters(phrase, blacklist) {

  const lowerPhrase = phrase.toLowerCase()
  const lowerBlacklist = blacklist.toLowerCase()
  const letters = lowerBlacklist.split('')
  
  for (const letter of letters){
    if (lowerPhrase.includes(letter)) return false
  }
  
  return true
} 

console.log(hasNoneLetters("Hello world", "ab")) // true
console.log(hasNoneLetters("Hello world", "abcD")) // false
console.log(hasNoneLetters("HeLlO world", "O")) // false

CodePudding user response：

You have to split the blacklist string into individual characters and compare every character in phrase with each upper- & lower-case character from blacklist. Something like this:

function hasNoneLetters(phrase, blacklist) {
  let forbidden = blacklist.split('');
  return forbidden.every(char => {
    return !phrase.includes(char.toLowerCase()) && !phrase.includes(char.toUpperCase());
  });
}



console.log('should be true', hasNoneLetters('Abracadabra', 'mstvz'));
console.log('should be false', hasNoneLetters('Abracadabra', 'c'));

CodePudding user response：

You can just convert two strings params to either lowercase or uppercase and then loop over every character in the blacklist string

function hasNoneLetters(phrase, blacklist) {
  blacklist.toLowerCase().split('').forEach(function(c) {
    if(phrase.toLowerCase().includes(c) {
       return true;
    } 
  });
  return false
}