JPMorgan Chase & Co. Web Developer Interview Questions and Answers

PHP has over 100 array functions and over 200 string functions.

• Array functions include: array_push(), array_pop(), array_merge(), array_slice(), etc.

• String functions include: strlen(), str_replace(), substr(), strtolower(), etc.

• PHP also has functions for working with regular expressions, dates, and more.

• The exact number of functions may vary depending on the version of PHP being used.

Ajax is a technique used to update parts of a web page without reloading the entire page. It stands for Asynchronous JavaScript and XML.

• Ajax allows for asynchronous communication between the client and server.

• It uses JavaScript to send and receive data from the server without interfering with the display and behavior of the existing page.

• Ajax can be used to dynamically update content, submit forms without refreshing th...read more

Query to find count of duplicate records in MySQL

• Use GROUP BY clause to group the records by the column(s) that may have duplicates

• Use HAVING clause to filter out the groups with count less than 2

• Use COUNT() function to count the number of records in each group

Helpers in CodeIgniter are utility functions that assist in common tasks and can be used throughout the application.

• Helpers are standalone functions that can be loaded and used anywhere in the application.

• They provide a way to avoid writing repetitive code by providing ready-to-use functions.

• CodeIgniter comes with a set of built-in helpers, such as URL, Form, File, and Date helpers.

• Custom helpers can also be created to...read more

MVC is a software architectural pattern that separates an application into three main components: Model, View, and Controller.

• Model represents the data and business logic of the application.

• View is responsible for displaying the data to the user.

• Controller handles user input, updates the model, and interacts with the view.

• MVC promotes separation of concerns and improves code organization and maintainability.

• Example: In...read more

array_merge merges two or more arrays into one, while array_combine creates an array by using one array for keys and another for its values.

• array_merge combines the values of two or more arrays into a single array

• array_combine creates an array using one array for keys and another for its values

• array_merge preserves numeric keys, while array_combine uses the first array for keys and the second for values

• array_merge can ...read more

MySQL has multiple storage engines including InnoDB, MyISAM, and more.

• MySQL has a pluggable storage engine architecture

• InnoDB is the default storage engine for MySQL

• MyISAM is another popular storage engine

• Other storage engines include Memory, CSV, and more

MyISAM is faster but doesn't support transactions, while InnoDB is slower but supports transactions and foreign keys.

• MyISAM is the default storage engine for MySQL, while InnoDB is an alternative.

• MyISAM is faster for read-heavy applications, while InnoDB is better for write-heavy applications.

• MyISAM doesn't support transactions or foreign keys, while InnoDB does.

• MyISAM uses table-level locking, while InnoDB uses row-le...read more