, Positive Numbers
, Function Wrapper
, Truthy Expressions
, Word Count
, New Folder
, Log Patch
, Loading Bar
, Fahrenheit Converter
, Shopping Cart
, A Tag
, ATM Locations
, Ban Users
, Bank Branches
, Cheapest Product
, Date Transform
, Employee Manager
, Hide Button
, Hospital Patients
, Index Performance
, Menu Items
, Merge Stock Index
, Movies Live
, Restaurant Menu
, SMS Messages
, Student Activities
, Youngest Child
, Log Parser
, Product Rating
, Row Appender
, Scale Font Size
, Manager Sales
, Delete Orders
, Average Salary
, Movie Genres
, Auto Show
, Array Search
, Department Report
, File Exists
, Stream Transform
, Run Sequentially
, Retry Request
, Weather Data
, Post Comment
, Table of Names
, Student Rankings
, Welfare Organization
, Student Max Score
An array is a container of a fixed number of objects of a similar type. It is a fundamental component of most programming languages.
Closures are an important concept in any programming language in which functions are first-class citizens.
Exceptions exist in most modern programming languages, making it important for a programmer to understand them and know how to handle them.
Dynamically accessing and updating user interface elements is an important part of most modern web applications.
Event-based design patterns are very common in modern applications, especially in the development of user interfaces.
A programmer should use a language as a tool, always taking advantage of language-specific data types and built-in functions.
SQL is the dominant technology for accessing application data. It is increasingly becoming a performance bottleneck when it comes to scalability. Given its dominance, SQL is a crucial skill for all engineers.
Conditional statements are a feature of most programming and query languages. They allow the programmer to control what computations are carried out based on a Boolean condition.
A database view is a result set that is defined by a stored query, the results of which can can also be queried. As a fundamental and widely used database construct, it's useful for candidates to understand how and when they should be used.
The string data structure is used to represent text. It is one of the most commonly used data structures. Therefore, every programmer should be skilled at string manipulation.
Monkey Patching is a method of either adding new or overriding existing functionality without the creation of a new type. As such it's an important tool for developers to be familiar with.
HTML5 is now supported in all modern browsers, making it important for front-end developers to know how to use its features.
Subqueries are commonly used in database interactions, making it important for a programmer to be skilled at writing them.
The UPDATE statement is used to modify the existing records in a table and is one of the most used operations for working with the database.
In Node.js, modules are a way to package applications into multiple pieces. As such, it's important for every developer to know how they work.
Events are the basic building block of Node.js. As such, they are important for all Node.js programmers.
Arithmetic is a fundamental branch of mathematics. An understanding of arithmetic concepts, and their application, is important for every candidate.
Iteration is the act of repeating a process, or cycling through a collection. Iteration is one of the fundamental flow control tools available to developers.
Getting and setting HTML attributes is one of the most common coding tasks of that changes something on a web page.
Constraints are used to define rules and relationships. They are applied to a dataset. A constraint may take many forms, such as x ≤ 5 in a programming language and a NOT NULL constraint in a SQL table definition.
The CREATE TABLE statement is used to create a new table in a database. It is an essential command when creating new database.
A database schema defines how data is stored in a database. An SQL database uses a schema to define tables consisting of rows and columns that use fixed data types to store data. Formalizing how data is stored is the first step towards building an application or service.
The SELECT statement is used to select data from a database. It is the most used SQL command.
The CREATE INDEX statement is used to create indexes for tables. Indexes are used to retrieve data from the database more quickly. They are very important for making performant queries.
The performance of an application or system is important. The responsiveness and scalability of an application are all related to how performant an application is. Each algorithm and query can have a large positive or negative effect on the whole system.
The ALTER TABLE statement is used to add, delete, or modify columns and constraints in an existing table. Alter table statements are important for all programmers who have to modify existing schemas.
An aggregate function is typically used in database queries to group together multiple rows to form a single value of meaningful data. A good programmer should be skilled at using data aggregation functions when interacting with databases.
Dialog box, a small window that pops-up, is a common way for communicating information to the user and prompting them for a response.
Knowing how to order data is a common task for every programmer.
A regular expression (regex) is a special text string for describing a search pattern. It is a common way for extracting data from text.
Everyone makes mistakes. A good programmer should be able to find and fix a bug in their or someone else's code.
LEFT JOIN is one of the ways to merge rows from two tables. We use it when we also want to show rows that exist in one table, but don't exist in the other table.
An object is a self-contained component which consists of methods and properties to make a particular type of data useful. Knowing how to create objects, and work with them, is an essential part of OOP.
Calling methods asynchronously is a common task for programmers.
The proper implementation and use of indexes are important for improving the performance of database queries.
The UNION operator is used to combine the result-set of two or more SELECT statements. It is often used when a report needs to be made based on multiple tables.
The GROUP BY statement groups rows by some attribute into summary rows. It is a common command when making various reports.
Even though most database insert queries are simple, a good programmer should know how to handle more complicated situations like batch inserts.
A normalized database is normally made up of multiple tables. Joins are, therefore, required to query across multiple tables.
Familiarity with data serialization to and from formats such as XML and JSON is important as it is commonly used for interprocess communication
Extensible Markup Language (XML) is a markup language that defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. The design goals of XML emphasize simplicity, generality, and usability across the Internet. This is one of the most used formats for exchanging data over the web.
JSON is an open-standard format that uses human-readable text to transmit data objects consisting of attribute-value pairs. It's the most common data format used for asynchronous browser/server communication.
Every programmer should be familiar with data-sorting methods, as sorting is very common in data-analysis processes.
Adding or modifying content is the most common task when developing dynamic web pages.
Styling user interfaces according to the specification is a daily routine for a front-end developer.
A CTE (Common Table Expression) is a temporary result set that can be referenced within another SELECT, INSERT, UPDATE, or DELETE statement. Recursive CTEs can reference themselves, which enables developers to work with hierarchical data.
The delete statement is used to delete records in a table and is one of the four basic CRUD functions (create, read, update, and delete) required for working with any persistent storage.
A callback is a piece of code that can be passed as an argument to another bit of code. It's a very common pattern that has a wide variety of uses, and as such it's important to understand.
A class is one of the most widely used and primary structures used in object-oriented programming. As such it's important for any developer to have a working knowledge of how to use it.
The CASE statement is SQL's control statement. It goes through conditions and returns a value.
A good programmer should be familiar with when to use recursive functions, since they can provide elegant solutions for complex problems.
A stream is a sequence of data elements made available over time. It is particularly useful for tasks that may benefit from being asynchronous, including tasks such as I/O processing or reading from a file, and as such is important for developers to understand.
The async function declaration defines an asynchronous function, which can await a response. Using the async-await pattern allows using asynchronous code while not losing readability or maintainability.
Asynchronous programming is a programming method used to to run tasks asynchronously. Running tasks asynchronously can improve performance and allow applications to feel more responsive. As such, it's important for all programmers who need to write performant or responsive applications.
Forms provide a method of grouping inputs and collecting user data. As such, they are important for all front end developers.