Introduction to JavaScript Spring 2011 Class 4

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Conditionals Continued: Switch Statement

Nesting a lot of if statements gets pretty ugly. Often you can avoid nesting with by using a switch statement instead.

 switch (userInput){
 	  case "a": 
 		  console.log("apple");
 		  break;
 	  case "b":
 		  console.log("bats!");
 	  case "c":
 		  console.log("cougar");
 	  case "d":
 		  console.log("drats!");
 		  break;
 	  default:
 		  console.log("nothin' to see here");
 }

Functions

Our simplest function defines a block of code (contained in {braces}) that we want to use over and over again.

 var chickens = 38;
 var livers = 43;
 
 function addEmUp1() {
 	  var mySum = chickens + livers;
 	  console.log("chickens + livers = " + mySum);
 }
 addEmUp1();

The problem with that example is that the variables are hardcoded. What if I wanted to add up something other than chickens and livers?

 function addEmUp2(myVar1, myVar2){
 	  var mySum = myVar1 + myVar2;
 	  console.log("chickens + livers = " + mySum); 
 }

That example is better, but what if I wanted to do something with the sum other than logging it to the console?

 addEmUp2(chickens, livers);
 addEmUp2(4, 9328);
 
 function addEmUp3(myVar1, myVar2){
 	  var mySum = myVar1 + myVar2;
 	  return mySum;
 }
 
 var myHolder = addEmUp3(chickens, livers);
 console.log(myHolder);
 console.log("I have " + addEmUp3(chickens, livers) + " livers");

Objects

declare a new object then assign properties

 var myObject = new Object;
 
 myObject.myString = "I'm object 1'";
 myObject.myNumber = 47;
 myObject.myBool = false;
 
 console.log(myObject);
 console.log(myObject.myString);

declare a new variable, and assign multiple properties to it, making it an object

 var myObject2 = {myString: "I'm Object 2", myNumber: 47, myBool: false};
 
 console.log(myObject2);
 console.log(myObject2.myString);

assign a method to an object that already exists

 myObject2.sayString = function(){
 	  console.log(this.myString);
 }
 myObject2.sayString();

declare a variable, and assign properties and a method to it

 var myObject3 = {myString: "I'm object 3", sayString: function(){
 	  console.log(this.myString + ", and my favorite number is " + this.myNumber);
 }, myNumber: 48};
 myObject3.sayString();

Home Work

Proposal for Project #1

Make an html page linked from your portfolio that has at least one paragraph that explains what your website for project 1 will be. Project one should start as a simple html site that empathies quiality over quantity. Javascript will be added to enhance the website with out interfering any of the standard functionality. I will show examples in class week 5 & 6.