ES6 - const (for objects and arrays)

Excerpt from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/const

// const also works on objects
const MY_OBJECT = {'key': 'value'};

// Attempting to overwrite the object throws an error
MY_OBJECT = {'OTHER_KEY': 'value'};

// However, object keys are not protected,
// so the following statement is executed without problem
MY_OBJECT.key = 'otherValue'; // Use Object.freeze() to make object immutable

// The same applies to arrays
const MY_ARRAY = [];
// It's possible to push items into the array
MY_ARRAY.push('A'); // ["A"]
// However, assigning a new array to the variable throws an error
MY_ARRAY = ['B']