Difference between Terser and UglifyJS

In this article, we will discuss the difference between Terser and UglifyJS. Before discussing their differences, we must know about the Terser and UglifyJS.

What is the Terser?

Terser is a toolkit of JavaScript parsers and compressors that is made especially for ES6+ syntax. Due to its effective code optimization capabilities and great performance, it has become increasingly popular in recent years. Because Terser is so good at minifying and manipulating contemporary JavaScript, developers working with ES6 later find it a must-have tool.

Terser suggests using it with Rollup for optimal results, which is a powerful module bundler. In contrast to other bundlers like Webpack, Rollup is made especially for making JavaScript library flat bundles that are highly effective. It produces smaller, more optimized code by fully utilizing ES2015 (ES6) modules. In addition to Terser's optimization process, developers can further reduce file sizes and improve the overall performance of their applications by bundling with Rollup.

What is the UglifyJS?

UglifyJS is one of the oldest and most widely used JavaScript minifiers, known for its robust feature set that includes variable renaming, dead code elimination, and general code compression. In the JavaScript community, it's been essential for a while, especially for projects that use ES5 syntax. The main support for ES5 provided by UglifyJS has become a constraint in modern development environments because JavaScript has advanced with more features in ES6 and beyond.

For developers working on outdated projects or those who don't need support for the newest JavaScript syntax, UglifyJS is still a dependable and efficient choice despite this. It works well at stripping out unnecessary characters, comments, and whitespace from JavaScript files, which reduces file sizes and boosts application speed in general as well as load times.

Key differences between Terser and UglifyJS

There are several key differences between Terser and UglifyJS. Some main differences are as follows:

Feature	Terser	UglifyJS
Purpose	JavaScript parser, mangler, and minified for ES6+ code.	JavaScript minifier and compressor, mostly for ES5.
ES6+ Support	Full support for ES6+ syntax (arrow functions, classes, modules, etc.).	Partial support for ES6+, with limitations when handling newer syntax.
Optimization Capabilities	Advanced optimizations for smaller file sizes, including dead code removal, tree-shaking, and module bundling.	Basic optimizations like variable renaming, and dead code elimination, but lacks modern JavaScript optimizations.
Project Compatibility	It is ideal for modern JavaScript libraries, frameworks, and projects that utilize ES6+ features.	It is primarily compatible with ES5-based older JavaScript libraries and projects.
Performance	Faster execution of contemporary features through high-performance minification for ES6+ codebases.	It performs well with ES5. However, due to its limited support, it is slower and less reliable when processing ES6+ code.
Compression Features	It has more aggressive compression force that is combined with sophisticated feature support to manage large code bases.	It has standard compression, but unable to utilize modern module systems or optimize more recent JavaScript syntax.
Mangle/Obfuscation	It supports obfuscation, property mangling, and advanced variable renaming for ES6+.	It has limits with ES6+, but supports basic obfuscation and variable renaming.
Custom Configuration	It allows deeper customization for modern building procedures, such as the preservation of specific variables or functionalities.	It provides flexibility, but not to the same extent or with as much attention to detail as Terser's newer to JavaScript.
Active Maintenance	Actively maintained, and supported by the most recent JavaScript standards with frequent updates and new feature additions.	Although being maintained, development has slowed down to mostly address bug fixes and small improvements.
Popularity	It is gaining popularity because of enhanced ES6+ tooling and modern JavaScript development.	An old utility that is still in wide use, particularly in environments and legacy projects that use older JavaScript.
Use Case	It is ideal for modern web applications or libraries that use ES5 and don't require support for more recent syntax (React, Angular, Vue, etc.).	It is best suited for legacy web applications or libraries that rely on ES5 and do not need modern syntax support.
File Size Output	It produces smaller file sizes because of advanced optimizations when used with tools like Rollup.	It has limited optimizations for modern features result in larger file sizes when handling ES6+ projects.

Conclusion:

In conclusion, Terser's ability to handle ES6+ features seamlessly has made it the go-to tool for developers who works with modern JavaScript frameworks like React, Angular, and Vue. Update compatibility with JavaScript in the future is ensured by its active maintenance.

In situations when adopting new features is less important than maintaining stability and backward compatibility, UglifyJS is nevertheless useful for older codebases and projects where the older syntax is not required. However, its limitations in dealing with modern syntax can become a bottleneck in more advanced projects.

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