10 things a JavaScript developer should know

JavaScript is the most important programming language used in contemporary software development. An estimated 95% of websites use JavaScript to present dynamic content to visitors. Despite the importance of JavaScript for web and mobile development, many hiring managers don't know what to look for in a JavaScript developer.

What to Look for in a JavaScript Developer

This guide will help executives interested in JavaScript development services and help select the right outsourcing partner and software developers for their projects.

Scope

There are two main types of scope in JavaScript: local scope and global scope. A solid understanding of code helps developers reduce the number of errors and create more readable code.

The term scope describes the visibility of variables, functions, and objects in a line of code during runtime. The principle is based on the idea that users should only have access to what they need at that moment – ​​and represents the Minimum Access Principle in practice.

Software engineers must understand the difference between local scope and global scope. They should also be able to articulate which situations each level of access is best for. Local scope refers to variables that can only be accessed by code within the function. On the other hand, global scope variables can be read and changed anywhere in the code, regardless of the location of the variables.

Many novice developers don't understand the concept of scope and why it is so important for JavaScript development. Be sure to ask detailed scope questions during the interview process. Alternatively, work with a JavaScript development service to create interview questions and screen candidates.

Flux control

Control flow describes the order in which a computer executes a set of instructions. This is a simple but vital concept for JavaScript developers.

The code typically runs in order, from the first line to the last. However, scripts often use conditional structures to change how the code is executed.

Take a standard website contact form, for example. When a visitor fills out the form and clicks submit, the script submits their information and generates a confirmation note for the user. However, if the form is not complete, the conditional structure will generate a note that one or more fields are mandatory.

This kind of conditional structure is almost always needed in JavaScript code, and it's what makes this language so extraordinary. Experienced developers must understand how JavaScript uses control flow to write error-free code and create interactive web applications that operate intuitively.

Error handling

Coding errors are an inevitable part of the software development process. No matter how experienced a programmer is – mistakes will happen. In fact, research has found that software engineers make, on average, “about 15 to 50 errors per 1,000 lines of code delivered.”

JavaScript errors are traditionally divided into two distinct categories: programming errors and actual errors. Quality developers must be able to identify the type of error and find a simple solution. Before making an offer to a developer, it's important to ask how they would respond to different situations. Ask how they would identify and fix syntax, runtime, and logic errors to learn more about their development approach.

Asynchronous Code

Asynchronous programming is a type of parallel programming that allows multiple actions to happen simultaneously. When a user initiates an action, the program continues running until it returns the result. This type of code is quite different from traditional synchronous programming. The standard approach had a user initiate an action – and the program would stop running until the result was returned. The main disadvantage associated with this approach is that a second request will not be initiated until the first is complete.

Because a program can perform multiple actions at the same time, asynchronous code can improve application performance and software responsiveness. It's important to ensure potential developers understand the difference between the two approaches. Ask them to explain the differences between the two types of code, as well as what situations each is best used for.

Functions

One of the main differences between JavaScript and other programming languages ​​is the importance of functions. JavaScript allows software engineers to create a standalone function in code. The ability to place functions anywhere in the code makes programming much easier and helps you create shorter, more compact codes.
Furthermore, JavaScript treats functions like any other objects. Because these objects are extremely flexible in JavaScript, developers can pass one function to another function as a parameter, something called a higher-order function. This allows software engineers to create more complex applications without having to write much more code.

Document Object Model

The Document Object Model (DOM) is a programming interface for HTML and XML documents. It is a tree of objects that the browser uses to build a model of the web page structure. The DOM is a live data structure and your modifications will immediately appear on the web page. This allows JavaScript to structure and style a website. By changing the DOM, developers can create pages that can be updated without needing to be updated – a feature that Facebook has made standard. Additionally, users can customize the webpage experience and change the homepage layout with ease.

Node.js

Node.js is an open-source JavaScript runtime environment that processes server-side code and provides everything needed to run a program. Before their launch in 2009, web applications operated according to the client/server model. Node.js helps increase speed by using server idle time and an event loop to complete other requests. Node.js also provides developers with APIs for event-driven I/O and asynchronous development. Additionally, the framework also operates in a chained event-based loop, allowing for non-blocking callbacks. All front-end JavaScript developers must understand the fundamentals of Node.js. This is because its event loop increases the speed of applications and is quickly becoming the industry standard. Be sure to ask about the developers' previous experience with the framework before extending a job offer.

Security

Software security is one of the most important topics in the technology industry. The number of cyberattacks has increased by more than 600% since 2005 – and is on pace to break records in 2019. Companies have responded to this crisis by investing resources in software security and working with JavaScript outsourcing companies to hire security experts. However, cybersecurity experts are not solely responsible for preventing data breaches. Every member of the development team must be focused on preventing software attacks.

The best software developers must understand the most important software security models used across the industry. Approaches like the Trustworthy Software Methodology and the Trustworthy Computing Security Development Lifecycle have decades of data demonstrating their success. Ask potential employees about their experience with popular security models and how they ensure software security is integrated into all phases of the development lifecycle.

Basic design

Every JavaScript developer should have at least a cursory knowledge of user interface (UI) and experience design (UX). User design was traditionally viewed as a separate category of development. However, modern software development methodologies such as Agile and Lean emphasize the importance of design during each step of the process. Additionally, small development teams require programmers willing to fill in gaps when necessary. Quality JavaScript developers must be willing to contribute to design considerations, since user design will have a huge impact on the success of their software. Software engineers with an interest in design help companies create beautifully designed software while saving money.

Front-end structure

Prospective JavaScript developers should be competent with one of the three most popular JavaScript frameworks, React.js, Angular.js, and Vue.js. These front-end web frameworks create user interfaces and are the most popular choices for web pages and applications.

An essential language

JavaScript is an essential programming language for developers interested in creating custom web, desktop, and mobile applications. Companies interested in building custom software should thoroughly vet candidates for their technical skills and know-how before extending a job offer.

Knowing exactly what a JavaScript developer does is not an easy task. Some companies are making the hiring process easier by working with JavaScript development companies to find candidates. These offshore JavaScript companies have the in-house expertise needed to properly evaluate developers and test knowledge. All finalized hires must have a solid understanding of JavaScript and be able to explain why each of the concepts above is essential knowledge.