<audio>, <video>, and <canvas>, although there are many others such as <article>, <summary>, <footer>, and more.<?php...?>, which can be shortened to <?...?> but is not recommended practice.// for a single-line comment or /*...*/ to span multiple lines.;).$.$variable = 1 is an assignment statement, whereas $variable == 1 is a comparison operator. Use $variable = 1 to set the value of $variable. Use $variable == 1 to find out later in the program whether $variable equals 1. If you mistakenly use $variable = 1 where you meant to do a comparison, it will do two things you probably don’t want: set $variable to 1 and return a true value all the time, no matter what its previous value was.$current-user would be harder to interpret if hyphens were also allowed in variable names and, in any case, would lead programs to be ambiguous.$This_Variable is not the same as $this_variable._ (underscore).++$j and $j++ unless the value of $j is being tested, assigned to another variable, or passed as a parameter to a function. In such cases, ++$j increments $j before the test or other operation is performed, whereas $j++ performs the operation and then increments $j.&& and and are interchangeable except where precedence is important, in which case && has a high precedence, while and has a low one.<<<_END..._END; construct to create a multiline echo or assignment. The closing tag must begin at the start of a line, and end with a semicolon followed by a new line.\' or \" to escape either a single or double quote.echo and print commands are similar in that they are both constructs, except that print behaves like a PHP function and takes a single argument, while echo can take multiple arguments.global.TRUE represents the value 1, and FALSE represents NULL, which can be thought of as “nothing” and is output as the empty string.if, switch, and the ?: operator.continue statement.for statements are more powerful than while loops, because they support two additional parameters to control the loop handling.if and while statements are literal (or Boolean) and therefore trigger execution when they evaluate to TRUE. Numeric expressions trigger execution when they evaluate to a nonzero value. String expressions trigger execution when they evaluate to a nonempty string. A NULL value is evaluated as false and therefore does not trigger execution.include or require directives, or their safer variants, include_once and require_once.To create a new object in PHP, use the new keyword like this:
$object = new Class;
To create a subclass, use the extends keyword with syntax such as this:
class Subclass extends Parentclass ...
__construct within the class and place your code there.array keyword is that it enables you to assign several values at a time to an array without repeating the array name.each function and the foreach...as loop construct return elements from an array; both start at the beginning and increment a pointer to make sure the next element is returned each time; and both return FALSE when the end of the array is reached. The difference is that the each function returns just a single element, so it is usually wrapped in a loop. The foreach...as construct is already a loop, executing repeatedly until the array is exhausted or you explicitly break out of the loop.count function to count the number of elements in an array.explode function is to extract sections from a string that are separated by an identifier, such as extracting words separated by spaces within a sentence.reset function.%f.To take the input string "Happy Birthday" and output the string "**Happy", you could use a printf statement such as this:
printf("%'*7.5s", "Happy Birthday");
printf to a variable instead of to a browser, you would use sprintf instead.To create a Unix timestamp for 7:11 a.m. on May 2nd, 2016, you could use the following command:
$timestamp = mktime(7, 11, 0, 5, 2, 2016);
w+ file access mode with fopen to open a file in write and read mode, with the file truncated and the file pointer at the start.The PHP command for deleting the file file.txt is as follows:
unlink('file.txt');
file_get_contents is used to read in an entire file in one go. It will also read them from across the Internet if provided with a URL.$_FILES contains the details about uploaded files.exec function enables the running of system commands.<hr />) or the standard HTML4 style (such as <hr>). It’s entirely up to you or your company’s coding style.SHOW databases. To see tables within a database that you are using, type SHOW tables. (These commands are case-insensitive.)To create this new user, use the GRANT command like this:
GRANT PRIVILEGES ON newdatabase.* TO 'newuser'@'localhost' IDENTIFIED BY 'newpassword';
DESCRIBE tablename.FULLTEXT index enables natural-language queries to find keywords, wherever they are in the FULLTEXT column(s), in much the same way as using a search engine.FULLTEXT index or using in searches. However, it does participate in a search when it is part of a larger string bounded by double quotes.SELECT DISTINCT essentially affects only the display, choosing a single row and eliminating all the duplicates. GROUP BY does not eliminate rows, but combines all the rows that have the same value in the column. Therefore, GROUP BY is useful for performing an operation such as COUNT on groups of rows. SELECT DISTINCT is not useful for that purpose.To return only those rows containing the word Langhorne somewhere in the column author of the table classics, use a command such as this:
SELECT * FROM classics WHERE author LIKE "%Langhorne%";
The three rules of First Normal Form are as follows:
There should be no repeating columns containing the same kind of data.
All columns should contain a single value.
There should be a primary key to uniquely identify each row.
BEGIN or the START TRANSACTION command. To terminate a transaction and cancel all actions, issue a ROLLBACK command. To terminate a transaction and commit all actions, issue a COMMIT command.EXPLAIN command.To back up the database publications to a file called publications.sql, you would use a command such as:
mysqldump -u user -ppassword publications > publications.sql
mysqli, call the mysqli method, passing the hostname, username, password, and database. A connection object will be returned on success.mysqli, ensure you have first created a connection object to a database, and call its query method, passing the query string.mysqli error occurs, the error property of the connection object contains the error message. If the error was in connecting to the database, then the connect_error property will contain the error message.mysqli query, use the num_rows property of the result object.mysqli results, call the data_seek method of the result object, passing it the row number (starting from 0); then call the fetch_array or other retrieval method to obtain the required data.real_escape_string method of a mysqli connection object, passing it the string to be escaped.mysqli methods, your programs carry the risk of running out of memory, especially on high-traffic websites. If there’s a program flow logic error in your code, it also ensures you won’t accidentally access old results.$_GET for the GET method and $_POST for the POST method.register_globals setting was the default in versions of PHP prior to 4.2.0. It was not a good idea, because it automatically assigned submitted form-field data to PHP variables, thus opening up a security hole for potential hackers who could attempt to break into PHP code by initializing variables to values of their choice.choices[], instead of a regular field name. Each value is then placed into the array, whose length will be the number of elements submitted.type="hidden".<label> and </label> tags.htmlentities function.autocomplete attribute, which prompts the user with possible values.required attribute to essential inputs.set_cookie function.set_cookie, but set its expiration date in the past.$_SERVER['PHP_AUTH_USER'] and $_SERVER['PHP_AUTH_PW'].hash function is a powerful security measure, because it is a one-way function that converts a string to a 32-character hexadecimal number that cannot be converted back, and is therefore almost uncrackable.hash conversion. This makes it nearly impossible for a brute-force dictionary attack to succeed.session_start function.<script> and </script> tags.<script src='filename.js'> tag.echo and print commands used in PHP is the JavaScript document.write function (or method).// for a single-line comment or surround it with /* and */ for a multiline comment.+ symbol.var keyword upon first assignment.To display the URL assigned to the link ID thislink in all main browsers, you can use the two following commands:
document.write(document.getElementById('thislink').href)
document.write(thislink.href)
The commands to change to the previous page in the browser’s history array are:
history.back() history.go(-1)
To replace the current document with the main page at the oreilly.com website, you could use the following command:
document.location.href = 'http://oreilly.com'
TRUE, true, FALSE, and false, whereas only true and false are supported in JavaScript. Additionally, in PHP, TRUE has a value of 1, and FALSE is NULL; in JavaScript they are represented by true and false, which can be returned as string values.$) to define a JavaScript variable name. JavaScript variable names can start with and contain uppercase and lowercase letters as well as underscores; names can also include digits, but not as the first character.if, switch, and the ?: operator.if and while statements are literal or Boolean and therefore trigger execution when they evaluate to TRUE. Numeric expressions trigger execution when they evaluate to a nonzero value. String expressions trigger execution when they evaluate to a nonempty string. A NULL value is evaluated as false and therefore does not trigger execution.for statements are more powerful than while loops, because they support two additional parameters to control loop handling.with statement takes an object as its parameter. Using it, you specify an object once; then for each statement within the with block, that object is assumed.Count, count, and COUNT are all different.arguments array, which is a member of all functions.this keyword to refer to the current object.this object within the class definition.new keyword.prototype keyword to create a single instance, which is then passed by reference to all the objects in a class.The syntax you would use to create an associative array is key : value, within curly braces, as in the following:
assocarray =
{
"forename" : "Paul",
"surname" : "McCartney",
"group" : "The Beatles"
}
A statement to sort an array of numbers into descending numerical order would look like this:
numbers.sort(function(a, b){ return b – a })
onsubmit attribute to the <form> tag. Make sure that your function returns true if the form is to be submitted, and false otherwise.test method./[^\w]/, /[\W]/, /[^a-zA-Z0-9_]/, and so on./f[oi]x/./\w+\W/g.A JavaScript function using regular expressions to test whether the word fox exists in the string "The quick brown fox" could be as follows:
document.write(/fox/.test("The quick brown fox"))
A PHP function using a regular expression to replace all occurrences of the word the in "The cow jumps over the moon" with the word my could be as follows:
$s=preg_replace("/the/i", "my", "The cow jumps over the moon");
value, which is placed within an <input> tag and takes the form value="value".XMLHttpRequest objects, because Microsoft browsers use two different methods of creating them, while all other major browsers use a third. By writing a function to test the browser in use, you can ensure that code will work on all major browsers.try...catch construct is to set an error trap for the code inside the try statement. If the code causes an error, the catch section will be executed instead of a general error being issued.XMLHttpRequest object has six properties and six methods (see Tables 17-1 and 17-2).readyState property of an object has a value of 4.status will have a value of 200.responseText property of an XMLHttpRequest object contains the value returned by a successful Ajax call.responseXML property of an XMLHttpRequest object contains a DOM tree created from the XML returned by a successful Ajax call.XMLHttpRequest object’s onreadystatechange property. You can also use an unnamed, inline function.XMLHTTPRequest object’s send method is called.GET and POST request are that GET requests append the data to the URL and not as a parameter of the send method, and POST requests pass the data as a parameter of the send method and require the correct form headers to be sent first.To import one style sheet into another, you use the @import directive, like this:
@import url('styles.css');
To import a style sheet into a document, you can use the HTML <link> tag:
<link rel='stylesheet' type='text/css' href='styles.css'>
To directly embed a style into an element, use the style attribute, like this:
<div style='color:blue;'>
# character (e.g., #myid), and class names with a . character (e.g., .myclass)./* and */ opening and closing comment markers.* universal selector.Given a pair of CSS declarations with equal precedence, to make one have greater precedence over the other, you append the !important declaration to it, like this:
p { color:#ff0000 !important; }
^=, $=, and *= match the start, end, or any portion of a string, respectively.The property you use to specify the size of a background image is background-size, like this:
background-size:800px 600px;
You can specify the radius of a border using the border-radius property:
border-radius:20px;
To flow text over multiple columns, you use the column-count, column-gap, and column-rule properties or their browser-specific variants, like this:
column-count:3;
column-gap :1em;
column-rule :1px solid black;
The four functions with which you can specify CSS colors are hsl, hsla, rgb, and rgba; for example:
color:rgba(0%,60%,40%,0.4);
To create a gray text shadow under some text, offset diagonally to the bottom right by 5 pixels, with a blurring of 3 pixels, you would use this declaration:
text-shadow:5px 5px 3px #888;
You can indicate that text is truncated with an ellipsis by using this declaration:
text-overflow:ellipsis;
You include a Google Web Font in a web page by first selecting it from http://google.com/fonts. Then assuming, for example, you chose Lobster, include it in a <link> tag, like this:
<link href='http://fonts.googleapis.com/css?family=Lobster'
rel='stylesheet' type='text/css'>
and also refer to the font in a CSS declaration such as this:
h1 { font-family:'Lobster', arial, serif; }
The CSS declaration you would you use to rotate an object by 90 degrees is:
transform:rotate(90deg);
To set up a transition on an object so that when any of its properties are changed the change will transition immediately in a linear fashion over the course of half a second, you would use this declaration:
transition:all .5s linear;
O function returns an object by its ID, the S function returns the style property of an object, and the C function returns an array of all objects that access a given class.You can modify a CSS attribute of an object using the setAttribute function, like this:
myobject.setAttribute('font-size', '16pt')
You can also (usually) modify an attribute directly (using slightly modified property names where required), like this:
myobject.fontSize = '16pt'
window.innerHeight and window.innerWidth.onmouseover and onmouseout events.To create a new element, use code such as this:
elem = document.createElement('span')
To add the new element to the DOM, use code such as this:
document.body.appendChild(elem)
visibility property to hidden (or visible to restore it again). To collapse an element’s dimensions to zero, set its display property to none (the value block is one way to restore it).setTimeout function, passing it the code or function name to execute and the time delay in milliseconds.setInterval function, passing it the code or function name to execute and the time delay between repeats in milliseconds.position property to relative, absolute, or fixed. To restore it to its original place, set the property to static.$. Alternatively, you can use the method name jQuery.To link to minified release 1.11.1 of jQuery from the Google CDN, you could use HTML such as this:
<script src='http://ajax.googleapis.com/ajax/libs/jquery/ 1.11.1/jquery.min.js'></script>
$ factory method accepts CSS selectors in order to build a jQuery object of matching elements.css method, supplying just a property name. To set the property’s value, supply a property name and a value to the method.To attach a method to the element elem’s click event to make it slowly hide, you could use code such as the following:
$('#elem').click(function() { $(this).hide('slow') } )
fixed, relative, or absolute to its position property.Methods can be run at once (or sequentially if animations) by chaining them together with periods, like this:
$('#elem').css('color', 'blue').css('background',
'yellow').slideUp('slow')
$('#elem')[0], or use the get method, like this: $('#elem').get(0).To display the sibling element immediately preceding one with the ID of news in bold, you could use this statement:
$('#news').prev().css('font-weight', 'bold')
You can make a jQuery Ajax Get request using the $.get method, like this:
$.get('http://server.com/ajax.php?do=this', function(data) {
alert('The server said: ' + data) } )
<canvas> tag.<audio> or <video> tags.To create a canvas element in HTML, use a <canvas> tag and specify an ID that JavaScript can use to access it, like this:
<canvas id='mycanvas'>
To give JavaScript access to a canvas element, ensure the element has been given an ID such as mycanvas, and then use the document.getElementdById function (or the O function from the OSC.js file supplied on the companion website) to return an object to the element. Finally, call getContext on the object to retrieve a 2D context to the canvas, like this:
canvas = document.getElementById('mycanvas')
context = canvas.getContext('2d')
To start a canvas path, issue the beginPath method on the context. After creating a path, you close it by issuing closePath on the context, like this:
context.beginPath() // Path creation commands go here context.closePath()
You can extract the data from a canvas using the toDataURL method, which can then be assigned to the src property of an image object, like this:
image.src = canvas.toDataURL()
To create a gradient fill (either radial or linear) with more than two colors, specify all the colors required as stop colors assigned to a gradient object you have already created, and assign them each a starting point as a percent value of the complete gradient (between 0 and 1), like this:
gradient.addColorStop(0, 'green') gradient.addColorStop(0.3, 'red') gradient.addColorStop(0,79, 'orange') gradient.addColorStop(1, 'brown')
To adjust the width of drawn lines, assign a value to the lineWidth property of the context, like this:
context.lineWidth = 5
clip method.bezierCurveTo method, supplying two pairs of x and y coordinates for the attractors, followed by another pair for the end point of the curve. A curve is then created from the current drawing location to the destination.getImageData method returns an array containing the specified pixel data, with the elements consecutively containing the red, green, blue, and alpha pixel values, so four items of data are returned per pixel.transform method takes six arguments (or parameters), which are in order: horizontal scale, horizontal skew, vertical skew, vertical scale, horizontal translate, and vertical translate. Therefore, the arguments that apply to scaling are numbers 1 and 4 in the list.<audio> and <video> tags.play and pause methods of an audio or video element.To request geolocation data from a web browser, you call the following method, passing the names of two functions you have written for handling access or denial to the data:
navigator.geolocation.getCurrentPosition(granted, denied)
To determine whether or not a browser supports local storage, test the typeof property of the localStorage object, like this:
if (typeof localStorage == 'undefined') // Local storage is not available}
localStorage.clear method.postMessage method to send information, and by attaching to the web worker object’s onmessage event to retrieve it.To inform a web browser that the document can be run offline as a local web app, create a file to use as a manifest; in that file, list the files required by the application, and then link to the file in the <html> tag, like this:
<html manifest='filename.appcache'>
preventDefault method in your ondragover and ondrop event handlers.To make cross-document messaging more secure, you should always supply a domain identifier when posting messages, and check for that identifier when receiving them, like this for posting:
postMessage(message, 'http://mydomain.com')
And this for receiving:
if (event.origin) != 'http://mydomain.com') // Disallow
You can also encrypt or obscure communications to discourage injection or eavesdropping.