<script type="text/javascript"> window.location = "http://www.yoursite.com/" </script>
JavaScript Redirect
PMA03:05
JavaScript System Dialogs alert(),confirm(),prompt()
PMA00:33
The browser is capable of invoking system dialogs to display to the user through the alert(),
confirm(), and prompt() methods. These dialogs are not related to the web page being displayed
in the browser and do not contain HTML. Their appearance is determined by operating system and/
or browser settings rather than CSS. Additionally, each of these dialogs is synchronous and modal,
meaning code execution stops when a dialog is displayed, and resumes
after it has been dismissed.
The alert() method has been used throughout this book. It simply
accepts a string to display to the user. When alert() is called, a
system message box displays the specifi ed text to the user, followed by
a single OK button.
Alert dialogs are typically used when users must be made aware of something that they have no
control over, such as an error. A user’s only choice is to dismiss the dialog after reading the message.
The second type of dialog is invoked by calling confirm(). A confi rm dialog looks similar to an
alert dialog in that it displays a message to the user. The main difference between the two is the
To determine if the user clicked OK or Cancel, the confirm() method
returns a Boolean value: true if OK was clicked, or false if Cancel
was clicked or the dialog box was closed by clicking the X in the
corner. Typical usage of a confi rm dialog looks like this:
if (confirm(“Are you sure?”)) {
alert(“I’m so glad you’re sure! “);
} else {
alert(“I’m sorry to hear you’re not sure. “);
}
If the OK button is clicked, prompt() returns the value in the text box; if Cancel is clicked or the
dialog is otherwise closed without clicking OK, the function returns null. Here’s an example:
var result = prompt(“What is your name? “, “”);
if (result !== null) {
alert(“Welcome, “ + result);
}
confirm(), and prompt() methods. These dialogs are not related to the web page being displayed
in the browser and do not contain HTML. Their appearance is determined by operating system and/
or browser settings rather than CSS. Additionally, each of these dialogs is synchronous and modal,
meaning code execution stops when a dialog is displayed, and resumes
after it has been dismissed.
The alert() method has been used throughout this book. It simply
accepts a string to display to the user. When alert() is called, a
system message box displays the specifi ed text to the user, followed by
a single OK button.
Alert dialogs are typically used when users must be made aware of something that they have no
control over, such as an error. A user’s only choice is to dismiss the dialog after reading the message.
The second type of dialog is invoked by calling confirm(). A confi rm dialog looks similar to an
alert dialog in that it displays a message to the user. The main difference between the two is the
To determine if the user clicked OK or Cancel, the confirm() method
returns a Boolean value: true if OK was clicked, or false if Cancel
was clicked or the dialog box was closed by clicking the X in the
corner. Typical usage of a confi rm dialog looks like this:
if (confirm(“Are you sure?”)) {
alert(“I’m so glad you’re sure! “);
} else {
alert(“I’m sorry to hear you’re not sure. “);
}
If the OK button is clicked, prompt() returns the value in the text box; if Cancel is clicked or the
dialog is otherwise closed without clicking OK, the function returns null. Here’s an example:
var result = prompt(“What is your name? “, “”);
if (result !== null) {
alert(“Welcome, “ + result);
}
JavaScript Variables
PMA00:25
Variables store a value you can refer to later in the script. Variable names
can be nearly any valid identifi er. A JavaScript identifi er is a word that
contains only letters, numbers, $, and _, and that doesn’t start with a
number.
Variables are a great demonstration of how statements and expressions
can be combined. You use a variable declaration statement to create a
variable.
var myVariable;
If you already have a variable, you can use a variable assignment expression
to assign it a value.
myVariable = 42;
42
You can combine a variable declaration with an assignment expression.
var myVariable = 42;
You can also string together several variable declarations with commas.
Don’t forget the commas, though! Leaving off a comma can have the
unintended side effect of declaring a global variable when you don’t
mean to do that.var variable1 = 4,
variable2 = 8,
variable3 = 15;
JavaScript has a relatively small number of built-in data types, including
these common types:
var myNumber = 42;
var myString = "A string of text";
var myBoolean = true;
var myArray = [myNumber, myString, myBoolean];
can be nearly any valid identifi er. A JavaScript identifi er is a word that
contains only letters, numbers, $, and _, and that doesn’t start with a
number.
Variables are a great demonstration of how statements and expressions
can be combined. You use a variable declaration statement to create a
variable.
var myVariable;
If you already have a variable, you can use a variable assignment expression
to assign it a value.
myVariable = 42;
42
You can combine a variable declaration with an assignment expression.
var myVariable = 42;
You can also string together several variable declarations with commas.
Don’t forget the commas, though! Leaving off a comma can have the
unintended side effect of declaring a global variable when you don’t
mean to do that.var variable1 = 4,
variable2 = 8,
variable3 = 15;
JavaScript has a relatively small number of built-in data types, including
these common types:
var myNumber = 42;
var myString = "A string of text";
var myBoolean = true;
var myArray = [myNumber, myString, myBoolean];
JavaScript Alert
PMA23:59
The JavaScript alert is a dialogue box that pops up and takes the focus away from the current window and forces the web browser to read the message.
1.
<form>
<input type="button" onclick=
"alert('Are you sure you want to call')"
value="See">
</form>
2.
function myFunc() {
alert("executing myFunc!");
return true;
}
3.
for (var i = 0; i < 10; i++) {
var link = document.createElement("a");
link.innerHTML = "Link " + i;
link.href = "#";
link.onclick = function() {
alert("This is link " + i);
return false;
};
document.body.appendChild(link);
}
1.
<form>
<input type="button" onclick=
"alert('Are you sure you want to call')"
value="See">
</form>
2.
function myFunc() {
alert("executing myFunc!");
return true;
}
3.
for (var i = 0; i < 10; i++) {
var link = document.createElement("a");
link.innerHTML = "Link " + i;
link.href = "#";
link.onclick = function() {
alert("This is link " + i);
return false;
};
document.body.appendChild(link);
}
Web Application with PHP
PMA06:28
PHP embedded in HTML
<html>
<head><title>Example 1</title></head>
<body>
<?php
/* If it is April 1st, we show a quote */
if (date('md' == '0401')) {
echo 'A bookstore is one of the only pieces of evidence we have '.
'that people are still thinking. <i>Jerry Seinfeld</i>';
} else {
echo 'Good morning!';
}
?>
</body>
</html>
The line
<?php
begins the PHP section embedded into the HTML code; the
line
?>
ends the PHP section. Notice that the code uses echo
to send the output.
When the text is so simple, the echo
statements are acceptable.
Creating A Function In Javascript
PMA05:44
The basic structure of a function looks like this:
function functionName() {
// the JavaScript you want to run
}
The keyword function lets the JavaScript interpreter know you’re creating a function—
it’s similar to how you use if to begin an if/else statement or var to create a variable.
function printToday()
{
var today = new Date();
document.write(today.toDateString());
}
The function’s name is printToday. It has just two lines of JavaScript code that retrieve
the current date, convert the date to a format we can understand
function functionName() {
// the JavaScript you want to run
}
The keyword function lets the JavaScript interpreter know you’re creating a function—
it’s similar to how you use if to begin an if/else statement or var to create a variable.
function printToday()
{
var today = new Date();
document.write(today.toDateString());
}
The function’s name is printToday. It has just two lines of JavaScript code that retrieve
the current date, convert the date to a format we can understand
Javascript Do While Loops
PMA05:40
There’s another, less common type of loop, known as a do/while loop. This type of
loop works nearly identically to a while loop. Its basic structure looks like this:
do {
// javascript to repeat
} while (condition) ;
do {
var luckyNumber = prompt('What is your lucky number?','');
luckyNumber = parseInt(luckyNumber, 10);
} while (isNaN(luckyNumber));
Save this file and preview it in a web browser. Try typing text and other nonnumeric
symbols in the prompt dialog box. That annoying dialog box continues
to appear until you actually type a number.
loop works nearly identically to a while loop. Its basic structure looks like this:
do {
// javascript to repeat
} while (condition) ;
do {
var luckyNumber = prompt('What is your lucky number?','');
luckyNumber = parseInt(luckyNumber, 10);
} while (isNaN(luckyNumber));
Save this file and preview it in a web browser. Try typing text and other nonnumeric
symbols in the prompt dialog box. That annoying dialog box continues
to appear until you actually type a number.
Javascript For Loops
PMA05:35
JavaScript offers another type of loop, called a for loop, that’s a little more compact
(and a little more confusing). For loops are usually used for repeating a series of
steps a certain number of times, so they often involve some kind of counter variable,
a conditional test, and a way of changing the counter variable. In many cases,
a for loop can achieve the same thing as a while loop, with fewer lines of code. For
example.
for (var num=1; num<=100; num++) {
document.write('Number ' + num + '<br>');
}
var days = ['Monday', 'Tuesday', 'Wednesday', 'Thursday','Friday', 'Saturday', 'Sunday'];
for (var i=0; i<days.length; i++) {
document.write(days[i] + ', ');
}
Since for loops provide an easy way to repeat a series of steps a set number of times,
they work really well for working through the elements of an array. The while loop
in Figure 3-5, which writes each item in an array to the page, can be rewritten using
a for loop,
(and a little more confusing). For loops are usually used for repeating a series of
steps a certain number of times, so they often involve some kind of counter variable,
a conditional test, and a way of changing the counter variable. In many cases,
a for loop can achieve the same thing as a while loop, with fewer lines of code. For
example.
for (var num=1; num<=100; num++) {
document.write('Number ' + num + '<br>');
}
var days = ['Monday', 'Tuesday', 'Wednesday', 'Thursday','Friday', 'Saturday', 'Sunday'];
for (var i=0; i<days.length; i++) {
document.write(days[i] + ', ');
}
Since for loops provide an easy way to repeat a series of steps a set number of times,
they work really well for working through the elements of an array. The while loop
in Figure 3-5, which writes each item in an array to the page, can be rewritten using
a for loop,
Javascript While Loops
PMA05:32
A while loop repeats a chunk of code as long as a particular condition is true; in other
words, while the condition is true. The basic structure of a while loop is this:
while (condition) {
// javascript to repeat
}
The first line introduces the while statement. As with a conditional statement, you
place a condition between the set of parentheses that follow the keyword while.
Say you want to print the numbers 1 to 5 on a page. One possible way to do that is
like this:
document.write('Number 1 <br>');
document.write('Number 2 <br>');
document.write('Number 3 <br>');
document.write('Number 4 <br>');
document.write('Number 5 <br>');
Notice that each line of code is nearly identical—only the number changes from line
to line. In this situation, a loop provides a more efficient way to achieve the same goal:
var num = 1;
while (num <= 5) {
document.write('Number ' + num + '<br>');
num += 1;
}
words, while the condition is true. The basic structure of a while loop is this:
while (condition) {
// javascript to repeat
}
The first line introduces the while statement. As with a conditional statement, you
place a condition between the set of parentheses that follow the keyword while.
Say you want to print the numbers 1 to 5 on a page. One possible way to do that is
like this:
document.write('Number 1 <br>');
document.write('Number 2 <br>');
document.write('Number 3 <br>');
document.write('Number 4 <br>');
document.write('Number 5 <br>');
Notice that each line of code is nearly identical—only the number changes from line
to line. In this situation, a loop provides a more efficient way to achieve the same goal:
var num = 1;
while (num <= 5) {
document.write('Number ' + num + '<br>');
num += 1;
}
Javascript Array
PMA05:30
You can access the contents of a simple variable just by using the variable’s name.
For example, alert(lastName) opens an alert box with the value stored in the variable
lastName. However, because an array can hold more than one value, you can’t just
use its name alone to access the items it contains. A unique number, called an index,
indicates the position of each item in an array. To access a particular item in an array,
you use that item’s index number. For example, say you’ve created an array with
abbreviations for the days of the week, and want to open an alert box that displayed
the first item.
var days = ['Mon', 'Tues', 'Wed', 'Thurs', 'Fri', 'Sat', 'Sun'];
alert(days[0]);
For example, alert(lastName) opens an alert box with the value stored in the variable
lastName. However, because an array can hold more than one value, you can’t just
use its name alone to access the items it contains. A unique number, called an index,
indicates the position of each item in an array. To access a particular item in an array,
you use that item’s index number. For example, say you’ve created an array with
abbreviations for the days of the week, and want to open an alert box that displayed
the first item.
var days = ['Mon', 'Tues', 'Wed', 'Thurs', 'Fri', 'Sat', 'Sun'];
alert(days[0]);