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Challenge 30: Unique Characters

curriculum/challenges/english/blocks/daily-coding-challenges-javascript/68af0687ef34c76c28ffa547.md

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--description--

Given a string, determine if all the characters in the string are unique.

  • Uppercase and lowercase letters should be considered different characters.

--hints--

allUnique("abc") should return true.

js
assert.isTrue(allUnique("abc"));

allUnique("aA") should return true.

js
assert.isTrue(allUnique("aA"));

allUnique("QwErTy123!@") should return true.

js
assert.isTrue(allUnique("QwErTy123!@"));

allUnique("~!@#$%^&*()_+") should return true.

js
assert.isTrue(allUnique("~!@#$%^&*()_+"));

allUnique("hello") should return false.

js
assert.isFalse(allUnique("hello"));

allUnique("freeCodeCamp") should return false.

js
assert.isFalse(allUnique("freeCodeCamp"));

allUnique("!@#*$%^&*()aA") should return false.

js
assert.isFalse(allUnique("!@#*$%^&*()aA"));

--seed--

--seed-contents--

js
function allUnique(str) {

  return str;
}

--solutions--

js
function allUnique(str) {
  let seen = '';
  for (let char of str) {
    if (seen.includes(char)) {
      return false;
    }
    seen += char;
  }
  return true;
}