JavaScript Variables and Data Types Worksheet

Question 1

Find a reference that lists all the keywords in the JavaScript programming language.

JavaScript Keywords

Question 2

True or false: keywords and variable names are NOT case sensitive.

false

Question 3

There are some rules for how you can name variables in JavaScript. What are they?

Use camel case for the variables. They are case sensitive. They can't have spaces. Can't start with a number, but can have a number in the variable.

Question 4

What is 'camelCase'?

Involves writing multiple words together without spaces. The uppercase letter looks like the camels hump.

Question 5

What are ALL the different data types in JavaScript (note that there are some that we did not discuss in class)?

Number, String, Boolean, BigInt, Undefined, Null, Symbol, Object

Question 6

What is a boolean data type?

Data type with only two answers, true and false

Question 7

What happens if you forget to put quotes around a string when you initialize a variable to a string value? How does JavaScript try to interpret this?
For example: var lastName = Jones;

It assumes the string is actually another variable being called to

Question 8

What character is used to end a statement in JavaScript?

Just a semicolon ";"

Question 9

If you declare a variable, but do not initialize it, what value will the variable store?

The value will be undefined

Question 10

What output will the following program produce? In other words, explain what you would see in the console log if you ran a program like this:


const firstTestScore = 98;
const secondTestScore = "88";
const sum = firstTestScore + secondTestScore;
console.log(sum);
console.log(typeof sum);

It will show the sum of the two scores, the data type will be a number.

Question 11

What output will the following program produce? In other words, explain what you would see in the console log if you ran a program like this:


const total = 99;
console.log("total");
console.log(total);

It will display the word total, and then underneath shows the total of 99.

Question 12

What is the difference between these two variables?


const score1 = 75;
const score2 = "75";

One is a string and the other is a number

Question 13

Explain why the this code will cause the program to crash:


const score = 0;
score = prompt("Enter a score");

This attempts to assign a new value to the const variable which is not possible.

Coding Problems

Coding Problems - See the 'script' element below this h1 element. You will have to write some JavaScript code in it.

Here are some tips to help you with the coding problems:

To do this assignment, you'll need to know how to open the brower's developer tools (press F12) and look at the console log.
Pay extremely close attention to syntax! One little syntax error can mess up your entire program.
After you complete each problem, refresh the page in the browser and look in the console your log message and for errors.
If you have an error in the console, check the line number of the error then look for syntax errors on that line (and the line before and the line after that line).
If you get stuck on this assignment, please ask for help! Dealing with syntax errors can be extremely frustrating for beginners. It takes a lot of effort and support to get comfortable with the syntax of a language. Don't be afraid to ask for help, your success in this class will depend on your willingness to get help!