All these 4 jQuery methods are used for attaching events to selectors or elements. But they all are different from each other.
.bind(): This is the easiest and quick method to bind events. But the issue with bind() is that it doesn’t work for elements added dynamically that matches the same selector. bind() only attach events to the current elements not future element. Above that it also has performance issues when dealing with a large selection.
.live(): This method overcomes the disadvantage of bind(). It works for dynamically added elements or future elements. Because of its poor performance on large pages, this method is deprecated as of jQuery 1.7 and you should stop using it. Chaining is not properly supported using this method.
.delegate(): The .delegate() method behaves in a similar fashion to the .live() method, but instead of attaching the selector/event information to the document, you can choose where it is anchored and it also supports chaining.
.on(): Since live was deprecated with 1.7, so new method was introduced named “.on()”. This method provides all the goodness of previous 3 methods and it brings uniformity for attaching event handlers.
All these methods .empty(), .remove() and .detach() are used for removing elements from DOM but they all are different.
.empty(): This method removes all the child element of the matched element where remove() method removes set of matched elements from DOM.
.remove(): Use .remove() when you want to remove the element itself, as well as everything inside it. In addition to the elements themselves, all bound events and jQuery data associated with the elements are removed.
.detach(): This method is the same as .remove(), except that .detach() keeps all jQuery data associated with the removed elements. This method is useful when removed elements are to be reinserted into the DOM at a later time.
document.ready() function is different from body onload() function for 2 reasons.
- We can have more than one document.ready() function in a page where we can have only one body onload function.
- document.ready() function is called as soon as DOM is loaded where body.onload() function is called when everything gets loaded on the page that includes DOM, images and all associated resources of the page.
Undeclared variables are those that do not exist in a program and are not declared. If the program tries to read the value of an undeclared variable, then a runtime error is encountered.
Undefined variables are those that are declared in the program but have not been given any value. If the program tries to read the value of an undefined variable, an undefined value is returned.
MySQLi is an improved version of the older PHP MySQL driver, offering various benefits.
The developers of the PHP programming language recommend using MySQLi when dealing with MySQL server versions 4.1.3 and newer
The MySQLi extension provides various benefits with respect to its predecessor, the most prominent of which are:
- An object-oriented interface
- Object Mapping
- Support for prepared statements
- Support for multiple statements
- Support for transactions
- Enhanced debugging support
- Embedded server support
- More powerful Functionality
phpMyAdmin is a free and open source tool written in PHP intended to handle the administration of MySQL with the use of a web browser. It can perform various tasks such as creating, modifying or deleting databases, tables, fields or rows; executing SQL statements; or managing users and permissions.
1) Execute sudo apt-get install phpmyadmin
2) Edit the file /etc/apache2/apache2.conf. and include the line Include /etc/phpmyadmin/apache.conf
3) Restart Apache sudo /etc/init.d/apache2 reload
- Web interface
- MySQL database management
- Import data from CSV and SQL
- Export data to various formats: CSV, SQL, XML, PDF (via the TCPDF library), ISO/IEC 26300 – OpenDocument Text and Spreadsheet, Word, Excel, LaTeX and others
- Administering multiple servers
- Creating PDF graphics of the database layout
- Creating complex queries using Query-by-Example (QBE)
- Searching globally in a database or a subset of it
- Transforming stored data into any format using a set of predefined functions, like displaying BLOB-data as image or download-link
- Live charts to monitor MySQL server activity like connections, processes, CPU/Memory usage, etc.
- Working with different operating systems.
Customer sessions stores data related to customer, checkout session stores data related to quote and order. They are actuall under one session in an array. So firstname in customer/session will be $_SESSION[‘customer’][‘firstname’] and cart items count in checkout/session will be $_SESSION[‘checkout’][‘items_count’]. The reason Magento uses session types separately is because once the order gets placed, the checkout session data information should get flushed which can be easily done by just unsetting $_SESSION[‘checkout’] session variable. So that the session is not cleared, just session data containing checkout information is cleared and rest all the session types are still intact.
The “magic” methods are ones with special names, starting with two underscores, which denote methods which will be triggered in response to particular PHP events. That might sound slightly automagical but actually it’s pretty straightforward, we already saw an example of this in the last post, where we used a constructor – so we’ll use this as our first example.
PHP functions that start with a double underscore – a “__” – are called magic functions (and/or methods) in PHP. They are functions that are always defined inside classes, and are not stand-alone (outside of classes) functions. The magic functions available in PHP are: __construct(), __destruct(), __call(), __callStatic(), __get(), __set(), __isset(), __unset(), __sleep(), __wakeup(), __toString(), __invoke(), __set_state(), __clone(), and __autoload().
- Initializing or uninitializing object data
- Processing access to undefined methods or properties
- Converting objects to string representation