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JavaScript 1

Projected Time

About 2 hours

  • 45 minutes for the video walkthrough of the slides
  • 60 minutes for the Independent Practice
  • 20 minutes for the Group Practice

Prerequisites

  • Techtonica's JS workshop
  • "Asking Good Questions" lesson
  • "Writing Readable Code" lesson
  • "Debugging" lesson

Motivation

JavaScript is used on the frontend of almost every website. It's also a widely-used scripting language that be used on the backend as well. The JavaScript lessons set a solid foundation in JavaScript basics so we can use the language in more robust ways in later lessons.

Objective

Apprentices will be able to

  • Create descriptive variable names
  • Store numbers and strings in variables
  • Perform math operations on numbers
  • Increment and decrement variables
  • Obtain a random number
  • Find the length of a string
  • Index into a string

Supplemental Materials

Lesson

JavaScript I (video walkthrough of slides)

  • Please watch the video the first time without working along with the demonstration. Just absorb the concepts. Then, you can watch the demonstration a second time and code with the instructor if you like.

JavaScript I (slides

Things to Remember

  • Strings are immutable, which means you can't get inside them and change the characters. The only way you can change the string that's associated with a particular variable name is to re-bind that variable name to an entirely new string.

  • In computer science, we usually begin counting with 0 instead of 1. When you are indexing into a string, JavaScript begins counting at 0. When you are finding the length of a string, JavaScript begins counting at 1.

Demonstration

Instructor demonstrates in the video walkthrough how to work with numbers and strings in JavaScript.

Independent Practice

Techtonica staff will assign pairs.

Activity: Basic Calculator

Concepts you've seen in this lesson that appear in this activity:

  • Numbers
  • Math operations
  • Strings

Concepts you've seen at Techtonica's JS workshop that appear in this activity:

  • if/else
  • defining functions
  • calling functions
  • comparison operators

Using REPL.it, write a function called calculate that takes in 3 arguments. You can choose the parameter names for the arguments.

  • The first argument should be a number
  • The second argument should be a string that contains one math operator (eg: '+' or '-' or '*' or '/' or '%')
  • The third argument should be a number

The calculate function should return the result of the math expression that you've specified using the arguments. You'll need to code the logic so the function knows how to handle all the various math operators.

For example, the function call might look like this: calculate(3, '+', 7) And in this example, the function should return 10.

Feel free to use any resource you like if you get stuck, including the Codecademy JavaScript course you went through at Techtonica's JS workshop.

Group Practice

Swap pairs, read your new pair partner's code, and do code reviews for each other. Did your second pair partner take a different approach than you did with your first pair partner? If so, how?

Swap pairs once more and repeat.

Challenge

Here are some other ways you can extend your calculator. Choose whichever one(s) sound most interesting to you!

  1. Add the ability to use a square root.
  2. Add the ability to use exponents.
  3. Add the ability to use constants, such as pi (3.14).
  4. Add the ability to operate on a third number.
  5. Incorporate a function from the Math library.

Check for Understanding