JavaScript Variables and Data Types Worksheet

Question 1

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

Mozilla

Question 2

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

True

Question 3

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

The first character must start with a letter, underscore, or dollar sign. It can also have no spaces and avoid reserved keywords.

Question 4

What is 'camelCase'?

It's used for variable and function names.

Question 5

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

Null, Undefined, Boolean, Number, BigInt, String, and Symbol.

Question 6

What is a boolean data type?

It's either a true or 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 would be an variable instead of a string and lastName will equal to Jones. JavaScript will interpret it as it's is undefined.

Question 8

What character is used to end a statement in JavaScript?

A semi-colon.

Question 9

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

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);

console.log(myResult);

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);

total 99

Question 12

What is the difference between these two variables?


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

The first one is numeric value and the second one is a string value.

Question 13

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


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

The score is declared as a constant and constant connot be reassigned after they have been initialized.

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!