Javascript (JS)

Java

  • Object-oriented (OO) programming language
  • Creates applications that run in a virtual machine or browser
  • Needs to be compiled

Javascript

  • OOP scripting language
  • Runs on a browser only
  • All in text

What does it mean to be a scripting language?

A scripting language is a programming language which is interpreted, rather than compiled, which means that scripting languages represent a subset of all programming languages.

What does it mean to be "object oriented"?

Object Oriented Programming (OOP) refers to using self-contained pieces of code to develop applications. We call these self-contained pieces of code objects, better known as Classes in most OOP programming languages and Functions in JavaScript.

  • Inheritance (objects can inherit features from other objects)
  • Encapsulation (each object is responsible for specific tasks).

What do I mean by this?

Javascript

The Basics

String

sequence of characters

Number

numerical values you can do math on

Let's take a look using:

  • var =
  • typeof
  • toString()
  • parseInt(), Number()
  • == vs ===
  • length

Let's open up our console

We're going to start with variables, numbers, and strings

Would you store a social security number as a number or a string?

?

Independent Practice

http://jsforcats.com/

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference

Don't forget to reference:

(stop when you reach the end of Values and Variables)

Choose 1 to do in Class:

http://codepen.io/brigittewarner/pen/zqZyzX

Hide and Show Functions

Let's pick it right back up with loops, arrays, objects, and functions

  • Javascripting: Warm-up with 'FOR LOOP' through 'FUNCTIONS'
  • Want to dig deeper?  http://superherojs.com/

Loops

For Loops

The for statement creates a loop that consists of three optional expressions, enclosed in parentheses and separated by semicolons, followed by a statement or a set of statements executed in the loop: initialization, condition, final expression

Example:

The following for statement starts by declaring the variable i and initializing it to 0. It checks that i is less than nine, performs the two succeeding statements, and increments i by 1 after each pass through the loop.

FizzBuzz:

Write a program that prints the numbers from 1 to 100. But for multiples of three print “Fizz” instead of the number and for the multiples of five print “Buzz”. For numbers which are multiples of both three and five print “FizzBuzz”

http://jsfiddle.net/camskene/Jkjf3/

Arrays

Arrays

List-like objects whose prototype has methods to perform traversal and mutation operations. Neither the length of a JavaScript array nor the types of its elements are fixed.

// javascript

upcomingShows = ["Dan Deacon", "Sharon Van Etten", "Nicholas Jaar"]

// ember template

<ul>
  {{#each upcomingShows as |show|}}
    <li class="upcoming-shows">{{show}}</li>
  {{/each}}
</ul>

Using Arrays with Javascript Frameworks/Libraries

http://jasonjl.me/blog/2015/04/18/rendering-list-of-elements-in-react-with-jsx/

Objects

Objects

A collection of properties, and a property is an association between a name (or key) and a value.

var object = {

    key: value

}

var planet = {

    "name": "Saturn",

    "planet_number": 6

}

var polygons = {

    triangle: {

        "sides": 3,

        "color": "blue",

        "types": [

            {"name": "equilateral", "regular": true},

            {"name": "isosceles", "regular": false},

            {"name": "scalene", "regular": false}

        ]

    },

    quadrilateral: {

        "sides": 4,

        "some_other_thing": null

     }

}

Functions

Functions

In JavaScript, functions are first-class objects, because they can have properties and methods just like any other object.

Values can be passed to a function, and the function will return a value. What distinguishes functions from other objects is that functions can be called.

http://www.w3schools.com/js/tryit.asp?filename=tryjs_farenheit_to_celsius

Conditionals

If/Else

A condition evaluates to either true or false

 

This allows us to control which statement (eg function) is run






  var blogPosts = ["post1", "post2", "post3"];
  var lengthOfArray = blogPosts.length;

  var showAll = function() {
    // some code that shows the entire list
  };

  var truncateList = function() {
    // some code that truncates the list
    // some code that adds a show more button
  };


  if ( lengthOfArray < 10 ) {
    showAll();
  else
   truncateList();
  }


  
 

Review

Assigning variables



  var number = 15;

  var string = "I am a string";

  var aStringOfNumbers = "15";

  var domObject = $("#someId"); // requires JQuery


 typeof(number) // number
 typeof(aStringOfNumbers) // string

 number == aStringOfNumbers // true

 number === aStringOfNumbers // false
 


  
 

Comparing variables

For Loop




  var imageCount = $("#slider > img").length  
  for (var i = 0; i < imageCount; i++) {
   // statement
  }


 var images = $("#slider > img");

 // [
 //   <img id="1" alt="start" src="images/smile-emoji.jpg">,
 //   <img id="2" alt="1" src="images/disappointed-emoji.png">, 
 //   <img id="3" alt="2" src="images/cry-emoji.png">
 // ]


  
 

Array

Object

 
  var myHonda = {
                  color: "red",
                  wheels: 4,
                  engine: { cylinders: 4, size: 2.2 }
                };
  
  myHonda.color
  // red
  
  myHonda.engines.size
  // 2.2

 var x = 11;
 var y = 12;

 function multiply(x, y) {
   return x * y;
 }

 // 132


  
 

Function

Demo

What I'll demo

  • Simple JQuery slider
  • Debugger
  • Console.log

CRUD

  • Create
  • Read
  • Update
  • Delete

CRUD

  • Create or add new entries
  • Read, retrieve, search, or view existing entries
  • Update or edit existing entries
  • Delete/deactivate existing entries

Common CRUD apps:

To-do lists, recipes, blogs, playlists, profile, new account, etc...

 

Anything you'd want an user to not only be able to read, but to also add, edit, or delete.

Activity: (CUD) Forms

  1. Create a gallery using screenshots of
    1. good and bad forms
    2. their validation/alert messages
    3. their interstitial (loading, processing, etc) states
  2. Share your gallery, ready to discuss your evaluation of what makes some forms better than others

Homework

  • Design single-page CRUD app - due April 18th
    • 3 "CUD" Forms (Inputs, Outputs, Buttons)
    • 1 R (non-creating, updating, deleting state for information)
  • Create single-page CRUD app using react.js - due May 2 

Resources:

https://react.rocks/tag/CRUD

http://buildwithreact.com/tutorial

https://reactforbeginners.com/

https://medium.com/@rajaraodv/a-guide-for-building-a-react-redux-crud-app-7fe0b8943d0f#.xjgubxxrb

Javascript (JS)

By brigittewarner

Javascript (JS)

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