Exceeding Array Bounds in JavaScript

When accessing array data with indices, the most common problem we can run into is exceeding the array's bounds.

Remember, the items of an array are indexed from 0 to length - 1. Any index which is not in this range is invalid.

When you try to access an item with an invalid index, JavaScript doesn't throw an error, but simply returns undefined:

let myArray = [1, 2, 3];

// Valid indices: 0, 1, 2
console.log(myArray[0]); // Output: 1
console.log(myArray[2]); // Output: 3

// Invalid indices: 3, 30, -1
console.log(myArray[3]); // Output: undefined
console.log(myArray[30]); // Output: undefined
console.log(myArray[-1]); // Output: undefined

As programmers, we always want to make sure that we don't exceed one array's bounds in our programs

Assignment
Follow the Coding Tutorial and let's play with some arrays.

Hint
Look at the examples above if you get stuck.