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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
// number
// 17
1 + 2 * 3 + 4
// number
// 64
// 1 + 2 * 3 + 4
800 / 80 / 8
// boolean
// NaN
// 800 / 80 / 8

400 > 200
// boolean
// false
// 400 > 200

1 !== 1
// boolean
// true
// 1 !== 1

true || false
// boolean
// true
// true || false
true && false
// boolean
// false
// true && false
20 % 6
// 2
// 20 % 6

"a" + "b"
// string
// 'ab'
// "a" + "b"

Problem Two

What will the following return?

typeof 4
// number
// 4

typeof "hello"
// string
// "hello"
typeof true
// boolean
// true

2 === 1 || 3 === 4
// false
// boolean

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	true
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 | !B | A && !B| !(A || B)| |-------|-------|-------|--------|------------| | true | false | true | true | false | | false | true | false | false | false | | false | false | true | false | true | | true | true | false | false | false |

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

// 3 * 2 // 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 // 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 // cater + pillar // 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