Function fundamentals

Homework

1. Functions
   • Read: Functions - reusable blocks of code
   • Read: Build your own function
   • Read: Function return values
   • Read: Function expression
   • Watch (by Steve Griffith):
     • Introduction to Functions in JavaScript
     • JavaScript Function Parameters
     • JavaScript Function Return Statements
2. Events
   • Read: Introduction to events
   • Watch: Introduction to JavaScript Event Listeners by Steve Griffith
   • Reference: MDN Event Reference
3. Scope
   • Watch: Variable Scope

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Morning reflection

Housekeeping

• Returned marks: CPNT 260 Assignment 4, CPNT 201 Assignment 2
• Week 7 is function week.
• Dailies Shoutouts
  • Shivani: Hamburger menu
• Cool app for visualizing Javascript that Erica found.
• Aidan made a Discord server for WBDV! Check the Slack channel (from Monday the 22nd) for details.

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1. Function fundamentals

Learning Objectives

• Define a function.
  • Understand the difference between function statements and function expressions.
  • Define a function with a function statement.
  • Define a function with a function expression.
• Understand the difference between function parameters and function arguments.
  • Define a function parameter with a default value.
• Recognize when a function is being invoked.
  • Pass a function as a value.
  • Invoke a function.
• Understand what a function return value is.
  • Define a function that returns a value.

Terminology

Function

A reusable set of statements that take an (optional) input and return an (optional) output.

Function Definition

The creation of a function, either as a function statement or a function expression.

Function Invocation

Calling or running a function, using trailing parentheses ().

Function Parameter

A named variable that a function accepts as (eventual) input. Parameters are defined when the function is created.

Function Argument

The actual variable passed to a function when it is invoked.

First-class Function

When a function is treated like any other value. All functions in Javascript are considered first-class and can be passed as arguments to other functions.

Materials

• Gists:
  • Defining Functions
  • Parameters vs arguments
  • Invocating a function
  • Return values

Key Takeaways

See relevant Gists above.

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2. Function examples

Learning Objectives

• Define a greet function that accepts a name and optional lang parameter.

Materials

• Sample Code: Simple greet function

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Open lab-time

1. Create a function that accepts an array as a parameter and returns a random item from that array.
2. Review the code you’ve created in CPNT 262 thus far. Are there any other useful snippets you can turn into functions?

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Tony’s goals for Lab-Time

• Convert old function sample code into Gists for Week 7.

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Dailies

• Submit today’s Codepen/repo/gist to the Dailies section (in Assessments) in Brightspace.