We've seen that you cannot reassign a constant variable in the case of a number

or a string.

The same goes for any value of a constant variable.

You cannot reassign strings, numbers, booleans, objects, and arrays.

Unlike strings, numbers and booleans, objects in arrays have methods and

properties that modify the objects or array.

Do they still work with const?

First, we'll declare a variable which is a constant called days.

This will contain an array with a single string, Monday.

Second, we'll declare another constant variable,

person, that contains an object's literal

with a first_name key, with the string Imogen.

Let's attempt to modify these in the console here.

First, days, Let's use the push method to add another date to the array.

It didn't error.

It returned the number 2, meaning the new array length.

If we type days and hit Enter, we get Monday and Tuesday returned.

Let's try and add a last_name property to the person object, Again no error.

When we type person and hit Enter, we get an object literal back

with the first_name and last_name properties.

So what's happening here?

Const doesn't prevent complex objects like arrays and objects from being modified.

It just prevents them from being reassigned or overwritten completely.

For example, when I attempt to overwrite

person with another object literal.

It shows an error, because I'm attempting to reassign person with a new object.

However, if I modified the first_name,

To equal another value, Andrew, I don't get any errors.