Covered Skills
Testing of these skills is covered in this pre-built test because they’re closely related. On our paid plan, you can easily create your own custom multi-skill tests.
JavaScript
JavaScript
JavaScript is the programming language of HTML and the web. It's an essential skill for any programmer working with websites and web technologies.
Closures
Closures
Closures are an important concept in any programming language in which functions are first-class citizens.
HTML/CSS
HTML/CSS
HTML is the standard markup language for creating web pages. It's an essential skill for anyone creating web pages of any complexity.
CSS Selectors
CSS Selectors
Selectors are a programming pattern that can be used to select an element from a container. They are primarily used in technologies such as CSS and jQuery to apply styles to groups of elements.
Styling
Styling
Styling user interfaces according to the specification is a daily routine for a front-end developer.
Language
Language
A programmer should use a language as a tool, always taking advantage of language-specific data types and built-in functions.
Element Spacing
Element Spacing
Setting the margins and padding of the elements on a web page is one of the basic things that any web developer or designer should know.
Flexbox
Flexbox
The Flexible Box Layout Module makes it easier to design a flexible responsive layout structure.
Positioning
Positioning
Dynamic positioning of user interface elements depending on resolution is more important than ever in modern applications, making this important for a front-end developer.
Fonts
Fonts
Setting the font name or size is part of creating any web page.
Elements and Attributes
Elements and Attributes
Defining elements and their attributes is the first process in creating an HTML page.
HTML5
HTML5
HTML5 is now supported in all modern browsers, making it important for front-end developers to know how to use its features.
Animation
Animation
Animation is the process in which images or objects are manipulated to appear as if they are moving. It's a powerful effect that is important for UI designers to understand and be able to use.
Forms
Forms
Forms provide a method of grouping inputs and collecting user data. As such, they are important for all front end developers.
Hyperlink
Hyperlink
Hyperlink, or simply a link, is a reference to data that the reader can follow by clicking or tapping. There's no web page without a hyperlink.
IFrame
IFrame
The HTML Inline Frame element (iframe) represents a nested browsing context, embedding another HTML page into the current one. Web developers often use it to display content within other content.
Algorithmic Thinking
Algorithmic Thinking
When designing and/or analyzing an algorithm or data structure, it is important to consider the performance and structure of an implementation. Algorithmic thinking is one of the key traits of a good programmer, especially one working on complex or performance-critical code.
Timing Events
Timing Events
JavaScript can be executed in time-intervals. JavaScript developers use timing events to delay the execution of certain code, or to repeat code at a specific interval. Knowledge of timing events is necessary to implement features that have time as a factor.
Exceptions
Exceptions
Exceptions exist in most modern programming languages, making it important for a programmer to understand them and know how to handle them.
Serialization
Serialization
Familiarity with data serialization to and from formats such as XML and JSON is important as it is commonly used for interprocess communication
XML
XML
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.
Dictionary
Dictionary
A dictionary (or associative array) is a data type composed of a collection of key-value pairs, where each possible key appears at most once in the collection. It is used when we need to access items by their keys.
Ajax
Ajax
Ajax, which initially stood for Asynchronous JavaScript And XML, is a programming practice of building complex, dynamic webpages using a technology known as XMLHttpRequest. Knowledge of Ajax is important for web developers.
HTTP
HTTP
The Hypertext Transfer Protocol is the foundation of data communication on the World Wide Web. As such, it's important for all developers who work on internet applications and websites to understand this.
Promise
Promise
In JavaScript, a Promise is an object representing the eventual completion or failure of an asynchronous operation. It allows associating handlers with an asynchronous action's eventual success value or failure reason. It is one of the commonly used asynchronous programming techniques in JavaScript.
Arrays
Arrays
An array is a container of a fixed number of objects of a similar type. It is a fundamental component of most programming languages.
CSS Advanced
CSS Advanced
Cascading Style Sheets are the styling language of the web. Knowledge about advanced CSS features is required for seasoned front-end developers.
Element Size
Element Size
Setting the size of the elements on a web page is one of the basic things that any web developer or designer should know.
JSON
JSON
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.
Pagination
Pagination
Pagination is the process of dividing data into discrete pages. It can be used to reduce the overhead of fetching large quantities of data, and as such, it is important when developing systems that fetch remote data.
Sorting
Sorting
Every programmer should be familiar with data-sorting methods, as sorting is very common in data-analysis processes.
Associative Arrays
Associative Arrays
An associative array (or dictionary) is a data type composed of a collection of key-value pairs, where each possible key appears at most once in the collection. It is used when we need to access items by their keys.
Classes
Classes
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.
Objects
Objects
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.
Bookmarks
Bookmarks
A bookmark is a hyperlink that points to a location within a document, which is defined by a name that is assigned to an element. Bookmarks are used when we need to jump to a specific location within a document.
Accessibility
Accessibility
Accessibility refers to the design of products, devices, services, or environments for people who experience disabilities. It's important for all designers and developers to know how to optimize for people who experience disabilities.
CSS Basics
CSS Basics
Cascading Style Sheets are the styling language of the web. Any good front-end developer requires a knowledge of basic CSS features.
Tables
Tables
A table stores data as rows and columns. From databases to HTML layouts, as a data structure they are ubiquitous. They are an important structure for developers to understand and know how to use.
Responsive Design
Responsive Design
Anyone who works with web should know how to properly implement responsive web design that makes web pages render well on a variety of devices and screen sizes.
UI
UI
An understanding of user interface design is important for any good front-end developer.
Dialog Box
Dialog Box
Dialog box, a small window that pops-up, is a common way for communicating information to the user and prompting them for a response.
Event Handling
Event Handling
Event-based design patterns are very common in modern applications, especially in the development of user interfaces.
Semantic Tags
Semantic Tags
Semantic HTML elements clearly describe their meaning in a human and machine readable way. They are used to improve page SEO.
Graphs
Graphs
Many real-life situations are best modeled by graphs. Therefore, an in-depth knowledge of graph data structures is important for a good programmer.
SQL
SQL
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.
Conditions
Conditions
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.
Views
Views
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.
Select
Select
The SELECT statement is used to select data from a database. It is the most used SQL command.
Create Index
Create Index
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.
Database Schema
Database Schema
A database schema defines how data is stored in a database. Fields are assigned fixed data types and restrictions. Formalizing how data is stored is an early step towards building an application or service.
Performance Tuning
Performance Tuning
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.
Alter Table
Alter Table
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.
Constraints
Constraints
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.
Create Table
Create Table
The CREATE TABLE statement is used to create a new table in a database. It is an essential command when creating new database.
Aggregation
Aggregation
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.
Subqueries
Subqueries
Subqueries are commonly used in database interactions, making it important for a programmer to be skilled at writing them.
Ordering
Ordering
Knowing how to order data is a common task for every programmer.
Bug Fixing
Bug Fixing
Everyone makes mistakes. A good programmer should be able to find and fix a bug in their or someone else's code.
Indexes
Indexes
The proper implementation and use of indexes are important for improving the performance of database queries.
Union
Union
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.
Group by
Group by
The GROUP BY statement groups rows by some attribute into summary rows. It is a common command when making various reports.
Update
Update
The update operation is used to modify existing entries in a database and is used with high frequency when dealing with mutable data.
Insert
Insert
Even though most database insert queries are simple, a good programmer should know how to handle more complicated situations like batch inserts.
Joins
Joins
A normalized database is normally made up of multiple tables. Joins are, therefore, required to query across multiple tables.
Left Join
Left Join
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.
Right Join
Right Join
RIGHT 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.
Delete
Delete
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.
SQL CASE
SQL CASE
The CASE statement is SQL's control statement. It goes through conditions and returns a value.
CTE
CTE
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.
Borders
Borders
Borders can be applied to most HTML elements within the body. This is one of the most used element decorations.
Inline Styles
Inline Styles
Inline styles are styles that are applied directly on elements. This is one of the ways for applying styles and for some scenarios, such as for email, is the only supported way.
Selectors
Selectors
Selectors are a programming pattern that can be used to select an element from a container. They are primarily used in technologies such as CSS and jQuery to apply styles to groups of elements.
Strings
Strings
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.
CSS Layout
CSS Layout
Cascading Style Sheets are the styling language of the web. For a front-end developer, a knowledge of CSS layouts is required.
Database Normalization
Database Normalization
Database normalization is the process of structuring a relational database in accordance with a series of so-called normal forms in order to reduce data redundancy and improve data integrity. It should be used to avoid undesirable side-effects such as update, insert, and delete anomalies.
Content Manipulation
Content Manipulation
Adding or modifying content is the most common task when developing dynamic web pages.
DOM Manipulation
DOM Manipulation
Dynamically accessing and updating user interface elements is an important part of most modern web applications.
Arithmetic
Arithmetic
Arithmetic is a fundamental branch of mathematics. An understanding of arithmetic concepts, and their application, is important for every candidate.
Iteration
Iteration
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.
Regex
Regex
A regular expression (regex) is a special text string for describing a search pattern. It is a common way for extracting data from text.
Attribute Manipulation
Attribute Manipulation
Getting and setting HTML attributes is one of the most common coding tasks of that changes something on a web page.
Recursion
Recursion
A good programmer should be familiar with when to use recursive functions, since they can provide elegant solutions for complex problems.
ECMAScript 2015
ECMAScript 2015
ECMAScript 2015 adds a significant number of features to JavaScript, including classes, modules and range based loops. As such it's important for any JavaScript developer to understand.
Asynchronous Calls
Asynchronous Calls
Calling methods asynchronously is a common task for programmers.
Callback
Callback
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.
Monkey Patching
Monkey Patching
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.
Java
Java
The Java programming language is a simple, modern, general-purpose, object-oriented programming language. Having a basic familiarity with the programming language used on the job is a prerequisite for quickly getting up to speed.
Queue
Queue
A queue is a collection of items that are maintained in a sequence and can be modified by the addition of entities at one end of the sequence and removal from the other end of the sequence. It is the collection to be used when first-in-first-out (FIFO) collection is needed.
Data Structures
Data Structures
Choosing the right data structure to solve a problem can have huge implications on the performance of an application. Knowing when to use a specific data structure is one of the most important skills for a programmer.
Linked List
Linked List
A linked list is a linear collection of data elements where each element points to the next. It is a data structure consisting of a collection of nodes which together represent a sequence. It is usually used for advanced scenarios where we need fast access to the next element, or when we need to remove an element from anywhere in the collection.
HashMap
HashMap
A HashMap (or dictionary) is a data type composed of a collection of key-value pairs, where each possible key appears at most once in the collection. It is used when we need to access items by their keys.
Dynamic Programming
Dynamic Programming
Dynamic programming methods for code optimization can be very useful to a programmer who understands them.
HashSet
HashSet
HashSet is container that stores unique elements in no particular order. This allows for fast checks to see if a value was already added.
Tree
Tree
A tree is a hierarchical structure defined recursively starting with the root node, where each node is a data structure consisting of a value, together with a list of references to other nodes (the "children"). A lot of problems can be solved efficiently with trees, which makes them important for developers.
StringBuilder
StringBuilder
Since a string is an immutable data structure, concatenating multiple strings can introduce significant performance penalties. Every experienced developer should know when to use StringBuilder instead of simply concatenating two strings to improve performances in such scenarios.
Recommended Job Roles
These are the job roles that we recommend for the HTML/CSS, JavaScript, Java Algorithms, and SQL online test.
Full-Stack Developer