Values, Types & Operators

Practice reading JS code and understanding what it does!

Learning Objectives

• Understand different types in javascript
• Practice reading code & understanding boolean logic
• Learn the various operators in javascript and what they do

Prerequisites

• Forking & cloning a repo from git
• Making a pull request

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Getting Started

1. Fork this repository
2. Clone the forked repository to your computer
3. cd to the cloned directory
4. code . to open the repo in VSCode
5. When you are done, commit and push your work to your forked copy
6. Make a pull request on github against the original repo

Instructions

For problems 1 and 2, write your answer in a comment (comments start with //) immediately below the line of code.

Example:

2 + 2
// number, 4

For problems 3-5, fill out the existing table or create a new one. See the table syntax guide

For problems 6-10, see the example in problem 6 and write your own answer below each question.

Problem One

What are the types of the following expressions and what do they evaluate to?

17
//literal, because the result is exactly what is typed. 
1 + 2 * 3 + 4
//operator arithmetic, 11
800 / 80 / 8
//operator arthmetic, 1.25 
400 > 200
//comparisson operators, true 
1 !== 1
//comparisson operators, false 
true || false
//logical operators OR, true 
true && false
//logical operators AND, false
20 % 6
//operator arthmetic, 2
"a" + "b"
//string + operator, "ab"

Problem Two

What will the following return?

typeof 4
// number
typeof "hello"
// string
typeof true
// boolean
2 === 1 || 3 === 4
// false

Problem Three

Create a truth table for the expression A || B.

For reference, here is a truth table for the expression A && B. You can fill out the last column. Don't worry about keeping the spacing exact.

A	B	A && B	A ll B
true	true	true	//true
false	true	false	//true
true	false	false	//true
false	false	false	//false

Problem Four

Create a truth table for the expression !A && !B.

For reference, here is a truth table for the expression A && !B. You can fill out the last column. Don't worry about keeping the spacing exact.

A	B	!B	A && !B	!A && !B
true	true	false	false	//false
false	true	false	false	//false
true	false	true	true	//false
false	false	true	false	//true

Problem Five

Create a truth table for the expression !(A || B). | A | B | (A || B) |!(A || B) | | ----- | ----- | ------- | -------- | | true | true | true | false |
| false | true | true | false | | true | false | true | false | | false | false | false | true |

Problem Six

Write a step-by-step evaluation for the following expression (remember order of operations): 2 + 3 * 2 + 1. For reference, here is a exp of a step-by-step evaluation:

1 + 2 + 3 + 4
3 + 3 + 4
6 + 4
10

2 + 3 * 2 + 1 2 + 6 + 1 8 + 1 9

Problem Seven

Write a step-by-step evaluation for the following expression (remember order of operations): 4 / 2 + 8 / 4. 4 / 2 + 8 / 4 2 + 8 / 4 2 + 2 4

Problem Eight

Write a step-by-step evaluation for the following expression: 'ca' + 'ter' + 'pi' + 'llar'. 'ca' + 'ter' + 'pi' + 'llar' 'cater' + 'pi' + 'llar' 'caterpi' + 'llar' 'caterpillar'

Problem Nine

Write a step-by-step evaluation for the following expression: 2 * 4 === 8 && 'car' + 'pool' === 'carpool'. 2 * 4 === 8 && 'car' + 'pool' === 'carpool 8 === 8 && 'car' + 'pool' === 'carpool' true && 'car' + 'pool' === 'carpool' true && 'carpool' === 'carpool' true && true true

Problem Ten

Write a step-by-step evaluation for the following expression: '1' + '2' + '3' - '1'. '1' + '2' + '3' - '1' '12' + '3' - '1' '123' - '1' 122