ja9-look / js-principles-scope-lab-london-web-111918

Scope Lab

Objectives

1. Understand the difference between const and let
2. Understand how functions determine scope in JavaScript

Introduction

Scuber's drivers are beginning to take some notes down about their customers. Use your knowledge of scope to access and change some of these variables.

Instructions

A word of warning. In this lab, you will practice doing some bad things. For example, we'll ask you to declare variables in global scope, and write functions that break down. We do this, because by testing the limits, and exposing the underbelly of a language you can better understand it, and know what to avoid in the future.

Ok, these are your tasks:

• customerName: Declare a variable in global scope called customerName using the var keyword.
• upperCaseCustomerName(): Write a function that accesses that global customerName variable, and uppercases it.
• setBestCustomer(): Write a function that when called, declares a variable called bestCustomer in global scope and assigns it to be 'not bob'. (Poor Bob.) Also, poor us, declaring a global variable from inside a function is one of those things we would never want to do normally, but is good for us to explore right now.
• overwriteBestCustomer(): See the consequences of declaring a variable in global scope, by writing a new function called overwriteBestCustomer() that changes that bestCustomer variable.
• leastFavoriteCustomer and changeLeastFavoriteCustomer(): Now declare a constant in global scope called leastFavoriteCustomer, be sure to assign it some initial value. Ok, now write a function called changeLeastFavoriteCustomer() that attempts to change that constant - notice what JavaScript does when you try to change the constant.

View Scope Lab on Learn.co and start learning to code for free.