JavaScript Variables and Data Types Worksheet

Question 1

Find a hyperlink for Javascript Commands

JavaScript Key Words

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?

Must begin with a letter, underscore or $ sign. Cannot be a reserved keyword. Case sensitive. Any Length

Question 4

What is 'camelCase'?

camelCaseLikeThis lowercase than uppercase

Question 5

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

Primitive Data Types, Composite Data types and Special data types.

Question 6

What is a boolean data type?

Represents logical entities, can be either 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;

JS will try and interpret Jones as a varible or indntifier rather than a string.

Question 8

What character is used to end a statement in JavaScript?

semi colon

Question 9

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

It will store the value as undefiened, it is delcared but not assigned to a value.

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 would be 9988

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);

Question 12

What is the difference between these two variables?


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

score1 is a number and score2 is a string

Question 13

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


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

It will crash because we are trying to re assign a value to a constant variable. Cant be changed once 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!