Basic Data Structures - Check For The Presence of an Element With indexOf()

JavaScript
1

Tell us what’s happening:

Describe your issue in detail here.

Your code so far

function quickCheck(arr, elem) {
  // Only change code below this line
if(arr.indexOf(elem)){
  return true
}else{
  return false
}
  // Only change code above this line
}

Why does truth appear? if there should be no

2

You appear to have created this post without editing the template. Please edit your post to Tell us what’s happening in your own words.

3

what is the output of indexOf?

4

outputs true, but should be false

5

no, indexOf outputs a number, which is the index of the thing you are searching or -1 if not present in the array

6

Also, be aware that 0 is considered a falsy value.

function indexOfCheck(arr, elem) {
  if (arr.indexOf(elem)) {
    return true;
  } else {
    return false;
  }
}

function includesCheck(arr, elem) {
  if (arr.includes(elem)) {
    return true;
  } else {
    return false;
  }
}

console.log(indexOfCheck(["firstElement"], "firstElement")); // false
console.log(includesCheck(["firstElement"], "firstElement")); // true
7

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