JavaScript Best Practices: Tips for Writing Better Code

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JavaScript code is very popular. But, if you are new to the language, you might struggle with messy, error-prone code that is incredibly difficult to debug and scale.

This can be especially problematic when you start working on more complex projects.

In the fast-paced world of web development, this is unacceptable.

To prevent yourself and others from having to spend unnecessary time and money, you need to implement certain best practices to ensure that your code is clean, efficient, and maintainable.

Some of these key best practices include modularization, preventing the use of global variables, and much more.

Let’s look into the details so that you understand how to avoid common pitfalls and optimize your JavaScript code.

Why Should You Use JavaScript Best Practices?

Benefits of Following Best Practices

There are a couple of reasons why you may benefit from learning the best practices of this open source programming language as a developer.

The first and most impactful benefit is that well-structured and standardized code is easier for you and others to read, understand, and maintain. This means that you can prevent bugs and that debugging is done faster.

Optimized code is ultimately of higher quality and ends up running more efficiently than it would otherwise. This means that it results in faster load times, which improves user experience.

Another benefit is that it makes collaboration easier. Whether you are working with a team or not, you always want to write consistent code so that anyone who looks at the code can understand and, perhaps, contribute.

Lastly, these practices also allow you to build scalable applications and prevent security vulnerabilities, resulting in more robust and secure websites or applications.

Our team is aware of all of these best practices. If you need assistance, consider our web app and mobile app solutions. We also provide assistance in connecting you with an individual developer for staff augmentation and even a dedicated team.

Common Mistakes to Avoid

There are some common mistakes that even the most experienced programmers and software engineers can easily fall into.

Ignoring Scope

The first is ignoring scope. This means that unintended variables can spring up and cause issues. Similarly, inconsistent naming conventions can make your codebase confusing and difficult to navigate.

Shorthand can also make things confusing, and as your code becomes more complex, it can take longer to carry out some commands. If you can, try to use longer, more descriptive names for your variables and code as consistently as possible.

Common mistakes to avoid in JavaScript including ignoring scope, inconsistent naming conventions, not using separate files, neglecting asynchronous code, and skipping testing.
Avoid common JavaScript mistakes like ignoring scope, inconsistent naming, mixing files, neglecting async code, and skipping testing.

Not Using Separate Files

The second most common mistake that I have seen is not putting your JavaScript into a separate file. It can be tempting to write it in a script tag within HTML, but that can make it very confusing and decrease readability.

If your JavaScript is kept in a separate file and linked, there is also the added benefit of being able to reuse your code.

Neglecting Asynchronous Code

Next is neglecting asynchronous code, which can lead to issues with callbacks. You need to avoid this if you want to make your code readable and manageable.

Lack of Comments and Documentation

To further maintain readability, you should make sure that you add comments and documentation. You might think it is not essential at the time of writing, but it can help you in the future.

Skipping Testing

The last common mistake that you need to keep in mind is skipping testing throughout the writing process. It is a lot easier to test smaller sections of code to make sure you pick up issues early.

Recommended Tools for Developing with JavaScript

Using the right tools can help you streamline your JavaScript development and keep you up to date with best practices easily.


Linters are a great tool for catching errors and making sure that coding standards are automatically enforced. ESLint is a great option.

Code Formatters

Then there are code formatters like Prettier, which can help you clean up your code and make it easier to read.

Version Control Systems

I always recommend using a version control system. It is crucial, regardless of what programming language you are using.

If you ever plan on managing code changes or collaborating with others, it’s important to track changes and work with different versions.

Package Managers

You can try to use package managers to help you manage dependencies. This will keep your project organized by making it easy to install, update, and remove libraries.

If you are hesitant to start using any new tools because of their unfamiliarity, I highly recommend trying to find video tutorials to help you get a better idea of their capabilities.

Recommended tools for JavaScript development including ESLint for linters, Prettier for code formatters, Git for version control systems, and npm or Yarn for package managers.
Discover recommended tools for JavaScript development, including linters, code formatters, version control systems, and package managers.

How to Avoid Global Variables in Your JavaScript Code?

Understanding Global Scope in JavaScript

Global Scope in JavaScript refers to the top-level context in which variables and functions are accessible from anywhere in your code.

For example, if you declare a variable but do not remember to use a keyword like ‘var’, ‘let’, or ‘const’, then it becomes part of the global scope.

This is bad because it can cause conflicts, especially if you are working with a very large codebase where you might inadvertently overwrite the global variables.

Techniques for Modularization

Modularization is a powerful technique that you can use to organize your code into discrete, manageable sections.

By breaking your code into smaller modules, you can avoid altering the global scope. This makes it a great best practice for dealing with global variables.

To achieve modularization, you can use ES6 modules. These are things like ‘import’ and ‘export’ statements. This ensures that only the exported variables and functions are accessible to the other parts of your application.

CommonJS modules are very popular for Node.js in particular and use the ‘require’ and ‘module.exports’ to help you organize your code.

Lastly, you can use Immediately Invoked Function Expressions (IIFE). Wrapping your code in these creates a local scope, which prevents variables from influencing the global scope.

Preventing the Use of Global Variables

The first step that you need to take in order to prevent the use of global variables, is to declare your variables properly.

You can use ‘let’, ‘const’, or ‘var’, but the first two are usually preferred because of their block scope and so that you prevent accidental reassignment. In fact, some people consider the var keyword quite outdated.

Another way to avoid global variables is to closures. Closures will allow you to create private variables and functions. The code becomes encapsulated.

Sometimes, you might have no choice but to use global variables. If this is the case, you can encapsulate them in a single global object. You do this by organizing them under a namespace object. This allows you to avoid naming collisions.

By setting up a default namespace, you can ensure that any global variables are confined to this single object.

Where possible, you should also make sure that you always declare functions at the beginning of your code or module.

This will ensure that you define as many functions as possible before you use them and that you don’t accidentally call functions before declaring them.

What Are the Best Practices for Asynchronous JavaScript Development?

Using Promises for Asynchronous Operations

Promises can improve how asynchronous operations are handled in both JavaScript and HTML.

Usually, you would use callback functions. But these can lead to callback hell or code that is deeply nestled and difficult to maintain.

In comparison, promises let you chain asynchronous operations in a linear and understandable fashion.

Real-World Scenarios and Best Techniques

In real-world scenarios, asynchronous JavaScript development usually involves multiple operations that depend on one another.

Based on this, the best technique is usually chaining promises, which ensures that each operation is finished before the next one begins.

If you have multiple asynchronous tasks that can act independently of one another, it might be best to execute them in parallel using ‘Promise.all()’.

Regardless of which one you decide to use when working with promises, it can sometimes be easier to alter your syntax so that it is more similar to synchronous syntax.

You can use ‘async’ and ‘await’ from ES8.

Managing Asynchronous Behavior in DOM Manipulation

You can manage asynchronous behavior by using DOM (Document Object Module) manipulation through careful management.

When you are creating asynchronous operations that affect DOM, you can use loading indicators. This will generate a visual indicator that will show users something is loading.

You should also show meaningful error messages or have some sort of fallback content to show users if there is an issue.

Likewise, you can use debouncing or throttling techniques to limit the amount of triggers that will set off your asynchronous sections of code.

For example, when handling userinput, debouncing can prevent excessive function calls and improve performance.

Lastly, you can use libraries like Redux or Vuex to help manage your fetched data and help your application react appropriately when data changes.

How to Optimize JavaScript Code for Better Performance?

Techniques for Optimizing Code Efficiency

You need to make sure that you optimize JavaScript code efficiency if you want to create fast and responsible apps.

One key technique that you can use is to try and avoid DOM manipulation whenever possible. This can be quite a slow process.

It is also very important that you pay attention to the amount of repaints and reflows that you have and that you reduce them wherever you can. Style changes and layout thrashing in CSS can also affect your performance so make sure to minimize them.

Another way to improve efficiency is to optimize loops by using ‘for’ instead of ‘forEach’.

Lastly, you need to make sure that when you iterate over arrays, you cache the array length in a variable.

Additionally, using static methods in your code can help improve efficiency, as they belong to the class rather than instances, reducing the memory footprint.

Working with Asynchronous Functions for Dynamic Web Development

Asynchronous functions are very important for building dynamic and responsive web apps. There are a couple of critical practices that you need to keep in mind to use them successfully.

First, you need to leverage promises and async/wait syntax, as we have already mentioned, to make your chord easier to read and manage.

Then, you need to optimize your API calls. By batching requests or using techniques like caching, you can reduce the number of API calls. This will help you avoid redundant network requests.

Then, you should use debouncing and throttling to limit the call rate of asynchronous functions and help prevent performance bottlenecks.

Lazy loading is a versatile technique that you can use for dynamic web development. With lazy loading, large resources like images are only loaded when they are needed. This reduces load times.

If you are dealing with server interactions, it is crucial to handle asynchronous data fetching efficiently. This ensures that the user experience remains smooth and that your application can manage data from the server without significant delays.

Scalability Considerations for Large JavaScript Projects

Scalability is very important to consider for all JavaScript programming. You need to focus on how easy it is to change the code, take on bigger loads, adapt it to different platforms, and so on.

To make sure your code is easy to maintain, focus on techniques like modularizing code and managing dependencies using ES6 modules or bundlers like Webpack.

Babel and Parcel are also great options for optimizing the build processes. They can help you by minifying your code, eliminating dead code, and handling your assets.

Additionally, you could adopt a component-based architecture for front-end applications. You can use frameworks like React or Vue.js for this approach. These also have libraries that will help you implement state management.

Here at, we have a large team of React.js developers who provide quality solutions to a variety of different clients. You can hire individual developers through us or reach out to us for an entire solution.

It is also a good idea to keep an eye on how your application is performing by using tools like Chrome DevTools or lighthouse, which will give you a good idea of when and where an issue arises.

Techniques for optimizing JavaScript code including minimizing DOM manipulation, optimizing loops, using static methods, lazy loading, and reducing repaints and reflows.
Learn techniques for optimizing JavaScript code, including DOM manipulation, loop optimization, static methods, lazy loading, and reducing repaints.

What Is the Importance of Using Strict Mode in JavaScript?

Enforcing Strict Syntax Rules in JavaScript Development

Strict mode is a way to use a restricted version of JavaScript. This helps you write code that is more optimized but also more secure.

To enable strict mode, you need to use the ‘”use strict”‘ directive at the start of your directive. In doing so, you will enforce a stricter parsing and error-handling process.

This means that you end up eliminating a lot of silent errors which, in turn, makes your code a lot easier to debug.

Benefits of Error Prevention and Code Quality Improvement

There are a couple of different benefits to using strict mode in JavaScript.

The first, as mentioned before, is that it becomes a lot easier to prevent common mistakes, and you enforce stricter parsing, which means code quality increases.

The second benefit is that you are prevented from using reserved keyword and variable names, which could cause issues in other versions.

Strict mode also does not allow certain actions that are considered to be insecure or error-prone. This makes it more difficult to use if you are used to working with ‘with’ statements, for example, but it is worth it for some.

And lastly, some JavaScript engines can optimize code more effectively if you use strict mode. This ensures that you reinforce the basics.

Common Mistakes Addressed by Using “use strict” Directive

One of the most common mistakes that is addressed is accidental global variables. It also prevents assignments from having non-writable properties, which helps you avoid silent errors.

Strict mode also addresses octal numeric literals by disallowing them. These would otherwise lead to confusion and bugs.

Especially when writing longer pieces of code, it can be easy to create functions with duplicated parameter names, which strict mode also prevents. This helps prevent logic errors.

And lastly, it will prevent you from accidentally deleting a property that cannot be deleted.

Final thoughts

By adopting these JavaScript best practices, you can write clean, efficient, and maintainable code.

Some of these best practices involve more advanced concepts like understanding modularization, avoiding global variables, and mastering asynchronous development, but it is all worthwhile if you are trying to build scalable applications.

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With over 10 years of experience in software outsourcing, Alex has assisted in building high-performance teams before co-founding Trio with his partner Daniel. Today he enjoys helping people hire the best software developers from Latin America and writing great content on how to do that!
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