Add initial

Author: yanarchy

.gitignore

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+.DS_Store

intro-functions.md

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+# Intro to `function`s
+
+## Objectives
+
+1.  Know what a `function` is and why we have them
+1.  Create a `function`
+1.  Invoke a `function`
+1.  Know the difference between a `return` statement and `console.log`
+
+## Lecture Slides
+
+[Slides are here](https://docs.google.com/presentation/d/e/2PACX-1vSo5deQKWpUrkPQx4DsKRVmSB1kzr0fvN4hf5GGDG1Ic8dk-_PtLFbqzFuSEwpfCtNYhEGy82oMiRyA/embed?start=false&loop=false&delayms=10000)
+
+## Exercises
+
+### Explore Your Template
+
+1. Download this zip to get started with the exercises below.
+1. Unzip the contents.
+1. Working with the person next to you, try to see if you can figure out how to open the `your-template` folder on Visual Studio Code.
+1. Once you have the folder contents open on Visual Studio Code, take a look at the contents! What do you see?
+1. For the exercises below, you will do them in the `.js` file.
+
+### Basic Requirements
+
+// <-- Two backslashes mark a comment and comments are ignored by the JavaScript engine (the program which reads our code and does stuff.)
+
+```js
+// This line is a comment and not code.
+// This line is also a comment.
+```
+
+You can also surround multiple lines of comments with a backslash and asterisk
+
+```js
+/* This is more than one line of comments
+In fact it is two lines */
+```
+
+1.  Now that we are writing our JavaScript in a file rather than directly in the console, we will need to use `console.log` to make sure that values print in our console. Enter the following two lines into your **script.js** file. Open the **index.html** file in your browser and open the developer tools. What do you see in your developer console?
+
+    ```js
+    5 + 6;
+    console.log(6 + 6);
+    ```
+
+    Why does it work this way?
+
+1.  Use the `function` below to return the sum of two `number`s. Enter the following code in your script.js file:
+
+    ```js
+    function add(numOne, numTwo) {
+      return numOne + numTwo;
+    }
+
+    // Tests
+    console.log(add(4, 3)); // should return 7
+    console.log(add(100, 42)); // => 142
+    ```
+
+    **Something Cool**: `function`s that you declare in your **script.js** are available in the console. Try entering the two tests directly in the developer console. You should continue to put your tests in the **script.js** file, but this can be useful when debugging.
+
+1.  Declare a function named _subtract_ that subtracts the second argument from the first argument. Remember to try the test cases to see if your function works.
+
+    ```js
+    function subtract(num1, num2) {
+      // your code here
+    }
+    ```
+
+    Test cases:
+
+    ```js
+    console.log(subtract(4, 3)); // => 1
+    console.log(subtract(100, 42)); // => 58
+    ```
+
+1.  Declare a `function` named _greeting_ that takes a name `string` as an argument and prints hello!
+
+    ```js
+    // Your code here
+    ```
+
+    Test cases:
+
+    ```js
+    console.log(greeting("Alex")); // => "Hello, Alex!"
+    console.log(greeting("Beau")); // => "Hello, Beau!"
+    ```
+
+1.  Declare a `function` called _average_ that takes two `number`s as inputs and returns the average of those `number`s. This time, write two tests for your `function` by yourself!
+
+### Advanced Requirements
+
+1.  Check out [this pdf of geometry formulas](http://www.gbcnv.edu/documents/ASC/docs/00000005.pdf). Declare `function`s representing each of the formulas.