array.includes returning false where as searched name is in array

Question

If var c = familyArray.includes("Bart"); it will return false but if var c = familyArray.includes("Homer"); it will return true

I want it to be true in the case of Bart as well because it is also included in the array.

Below is my array:

var familyArray = ["Marge", "Homer", ["Bart", "Lisa", "Maggie"]];
var a = familyArray.indexOf("Bart");
var b = familyArray[2][0];
var c = familyArray.includes("Bart");

document.getElementById("demo").innerHTML = c;

console.log(a);
console.log(b);

<p id="demo"></p>

Answer 1

Your issue is that you have a multi-dimensional array, and array includes will not search the inner array. Thus, you need to flatten your array before searching it. Here I have used Infinity as a parameter in the case that your array has more dimensions than just 2:

var familyArray = ["Marge", "Homer", ["Bart", "Lisa", "Maggie"]];
var c = familyArray.flat(Infinity).includes("Bart");

console.log(c); // true;

See browser support for .flat() here. If you need better browser support you can use an alternative approach found here

Answer 2

You are using nested arrays, you can use .flat before hand:

familyArray.flat().includes('Bart')