More Javascript
CSIT570 10/10/13
LAST WEEK WE LEARNED ABOUT
- The DOM
- JavaScript vs Java
- How to embed JavaScript in HTML documents
- Types of and how to declare variables
- Operators
- Functions
- How to use user prompts to manipulate the DOM
This week, we will learn
-
control statements
- objects
- more about functions
- constructors
- debugging with browser developer tools
Control expressions
==
!=
<
>
<=
>=
===
!==
Control Statements
if/else
var x = true;
if ( x == true) {
console.log('true');
}
else {
console.log('false');
}
Control statements
switch
var x = "hello";
switch (x == "hello") {
case true:
console.log(x);
break;
case false:
console.log("bye");
break;
default: {
console.log("wowowow");
}
}
control statements
while loops
x = 0;
while ( x < 5 ) {
x++;
console.log(x);
}
control statements
do while loops
x = 0;
do { x++; console.log(x); } while ( x < 5);
control statements
for loops
for ( var x = 0; x < 5; x++) {
console.log(x);
}
Little exercise
write a for loop that goes from x=0 to x<10
within the for loop, if x is even, print x and "even" to the console.
if x is odd, print x and "odd" to the console.
objects
everything in JavaScript is an object
objects
var emptyObject = new Object();
Objects
we can add properties to objects
var myClass = new Object();
myClass.title = "CSIT 570";
myClass.dayOfWeek = "Thursday";
we can shorten this to:
var myClass = { title: "CSIT 570", dayOfWeek: "Thursday"};
Objects
we can put objects within objects
var myFamily = {
surname: "Schiffer",
sister: {
firstName: "Katie",
middleName: "Ann"
},
brother:{
firstName: "Danny",
middleName: "Judge"
}
};
Objects
what if:
more than one sister
more than one brother
objects
arrays
var myArray = new Array();
var myArray = new Array(1, 2, "one", 2);
or
var myArray = [];
var myArray= [1, 2,"one",2];
Objects
array properties & methods
myArray[0]
myArray.length
var arrayToCSVString = myArray.join(',');
myArray.sort();
myArray.push('3');
myArray.pop();
Objects
Let's use arrays
var myFamily = { surname: "Schiffer", siblings: [ { firstName: "Katie", middleName: "Ann"
}, { firstName: "Danny", middleName: "Judge" } ] };
An exercise with objects
conceptualize something as an object and create them in JavaScript. In my example, I made a family - you should come up with something new!
1. Your object should have at least 3 properties, one of which should also be an object.
objects: constructors
each object has a prototype
from that prototype they inherit a constructor
from that prototype they inherit a constructor
var myObject = new Object();
Objects: constructors
Let's create a Person constructor
function Person(first, last) {
this.firstName = first;
this.lastName = last;
};
Objects: constructors
Let's create a new Person object:
function Person(first, last) {
this.firstName = first;
this.lastName = last;
};
var jenn = new Person("jenn", "schiffer");
An exercise with constructors
Let's write a constructor for:
- A book
- A cat
- A pizza
And then let's declare 3 new objects of each constructor.
More Javascript
By Jenn Schiffer
More Javascript
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