Scope assignment in my own words

Scope questions

What is scope? Your explanation should include the idea of global vs. local scope.

The scope is what you are able to access within a group of code. Global scope refers to variables that are accessible everywhere, while the local scope is more specific. For example, if a variable is defined within a function, it is local to that function and no where outside of it. However, if a variable is defined outside of this function, it is global and you are able to access it in multiple functions. 

Why are global variables avoided?

Global variables make unintended side effects in a program more likely, meaning it will be harder to track down bugs in your code. There is just one global scope as opposed to the many local scopes that can be created (and bugs that can avoided from these multiple scopes).

Explain JavaScript's strict mode

Strict mode is a special feature of Javascript that gives an error message every time a variable is declared without the var keyword.

What are side effects, and what is a pure function?

A side effect is when a function reaches outside its local scope, up into a parent scope and alters a value that lives there. Functions with side effects do something other than returning a value. A pure function is a function that does not have any side effects.

Explain variable hoisting in JavaScript.

Hoisting takes all declarations of a variable inside of a particular scope and moves them to the top of the scope before it starts executing them. One thing to remember is that declarations are hoisted, but initializations are not.