let myArrayOne = ['one', 'two', 'three', 'four'],

    myArrayTwo = ['one', 'two', 'three', 'four'];

​

// remove Array element from each array

// using 2 different techniques

myArrayOne[2] = undefined;

delete myArrayTwo[2];

​

// same result, both have item as undefined

console.log(myArrayOne, myArrayTwo);

​

// length = 4 for both

console.log(myArrayOne.length, myArrayTwo.length);

​

// But the item doesn't exist in one array

console.log(2 in myArrayOne); // true

console.log(2 in myArrayTwo); // false