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?

By using const or let.

Question 4

What is 'camelCase'?

Making 2 words into one and having the 2nd word an upper case letter.

Question 5

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

Boolean, expression, and string.

Question 6

What is a boolean data type?

A value that can only be true or false nothing else.

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;

There will just be a bug or would not work.

Question 8

What character is used to end a statement in JavaScript?

A semicolon.

Question 9

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

The default variable will just 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);

I would see a big number because of the 98 and 88 and the word string because of the number 98 and the string 88 with the quotations around it.

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);

Would see the number 99 because that is the total when it is initialized.

Question 12

What is the difference between these two variables?


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

The one with no quotes is just a number and the one with quotes is a string.

Question 13

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


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

There was no score set below the "score = prompt" and no console.log either.

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!