freeCodeCamp/guide/english/certifications/javascript-algorithms-and-data-structures/basic-data-structures/check-for-the-presence-of-an-element-with-indexof/index.md

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Check For The Presence of an Element With indexOf()

Check For The Presence of an Element With indexOf()

• A simple if-statement can be used to check whether or not the value returned by the indexOf() function is less than 0.
• Once the value is discovered then you can return either true or false.
• Solution-1 demonstrates how a simple if-statement can return the correct result.

Solution-1:

function quickCheck(arr, elem) {
  if(arr.indexOf(elem)>=0) {
    return true;
  }
  return false;
}
console.log(quickCheck(['squash', 'onions', 'shallots'], 'mushrooms'));

• Solution-2 demonstrates how the problem can be solved using the ? : (conditional) operator.

Solution-2:

function quickCheck(arr, elem) {
return arr.indexOf(elem) >= 0 ? true : false;
}
console.log(quickCheck(['squash', 'onions', 'shallots'], 'mushrooms'));

• Solution-3 demonstrates how the problem can be solved by directly returning result of the comparison.

Solution-3:

function quickCheck(arr, elem) {
  return arr.indexOf(elem) != -1;
}
console.log(quickCheck(['squash', 'onions', 'shallots'], 'mushrooms'));