History of JavaScript

• 1995 – Brendan Eich at Netscape creates JavaScript
• 1996 – Netscape submits JavaScript to ECMA
• 2005 – Jesse James Garrett coins the term "Ajax"
• 2009 – ECMAScript 5 unifies JavaScript
• 2015 – ECMAScript 6 is standardized

Purpose of JavaScript

• General-purpose programming
• Common Uses
  1. Web browser scripting
  2. Server-side programming
  3. Mobile apps
  4. Hardware programming

JavaScript Difficulty Level

• Easy to get started with
• Difficult to master

JavaScript: The Good

• Dynamic
• Expressive
• Easy to read and write

JavaScript: The Bad

• Language oddities
  1. The == and != operators
  2. The eval function
• The name

JavaScript: The Future

• Better browser support for ES6 and beyond
• Reduced need for libraries like jQuery
• JavaScript engines will be faster
• JavaScript will likely remain the most popular language

Syntax

• Borrows from several other languages
• Java
• Awk
• Perl
• Python
• Case sensitive
• Statements are separated by semicolons

JavaScript Comments

• Two different kinds of comments
• Single line
  • // this is a comment
• Multi line
  • /* this is a comment it ends after the closing characters */

JavaScript Variables

• Declared using var
• Function scope
• ES6 and beyond
  • let creates block-scoped variables
  • const creates constants
• Dynamically typed

JavaScript Data Types

• Primitive data types
  1. Boolean
  2. number
  3. string
  4. null
  5. undefined

JavaScript Objects

• Collections of name: value pairs, separated by commas
• Each pair is a property
• Properties can be accessed in two ways
  • dot notation
    • myObj.property1 = "this is the value";
  • brackets notation
    • myObj['property2'] = "this is another value";

JavaScript Arrays

• Zero-indexed list objects
• Contain zero or more elements
• To create an array:
  • var trees = ['elm','pine','oak'];
• To access an array element:
  • trees[0] // 'elm'

JavaScript Functions

• Internal programs
• Have their own scope
• Can accept parameters
• Can return values

  • function myFunc(param1,param2){
    	var sum = param1 + param2;
    	return sum;
    }
    	myFunc(1,2) // 3

JavaScript Operators

• Arithmetic
  • +, -, *, /, %
• Comparison
  • >, <, >=, <=, ==, !=, ===, !==
  • "10" == 10 //true
  • "10" === 10 //false

JavaScript Loops

• for loop
  • for (var i=0; i<10; i++) { console.log(i); }
• while loop
  • while (i<10) { console.log(i); i= i+1; }
• do/while loop
  • do {console.log(i);i=i+1;} while(i<10);

JavaScript Conditional Statements

• if … else

  • if(price > 10) {
    		  …
    } else {
    		  …
    }

  • switch

    • switch(sandwich) {
      	case 'Ham':
      	price = 5;
      default:
      	price = 4;
      }

Keep Learning JavaScript

by taking a Webucator JavaScript Class

https://www.webucator.com/webdev-training/javascript-training.cfm

"I expected a comprehensive introduction to concepts of javascript, which is what I got!"