Comparison of JavaScript code style checking tools: JSLint, JSHint, JSCS and ESLint

This article will compare and analyze four popular JavaScript code style checking tools: JSLint, JSHint, JSCS and ESLint to help you choose the most suitable tool for your project. These tools help avoid coding errors by following coding specifications and identifying potential errors.

Key points:

• JSLint, JSHint, JSCS, and ESLint JavaScript code style checking tools such as JSLint, JSHint, JSCS and ESLint help avoid coding errors by following encoding standards and identifying potential errors. Each tool has its own advantages and disadvantages, and the choice of tool depends on the specific needs of the project.
• JSLint is the oldest tool designed to enforce good parts of JavaScript. It is not configurable and scalable, and lacks documentation. JSHint is a branch of JSLint, which is easier to configure and easy to use in large projects, but requires some setup to make it work.
• JSCS is a code style checker that focuses on code formatting, not potential errors. It has over 90 different rules and supports custom plugins. However, it is not as flexible as other tools and is the slowest of the four.
• ESLint is the latest, extensible tool with a lot of custom rules. It checks for errors and other issues in the code, so it is the recommended choice for the author. It supports ES6 features and JSX. However, its documentation can be confusing and requires some configuration.

Years of programming experience still make some low-level mistakes, such as spelling errors in variable names, grammar errors, and forgetting to handle errors correctly. A good code style checker tool can spot these problems before wasting time (or worse, client time). It can also help projects comply with coding specifications.

There are many JavaScript code style checking tools on the market, how to choose? Let's take a look at the features and advantages and disadvantages of four popular alternatives: JSLint, JSHint, JSCS and ESLint.

Overview

These four tools work basically the same way. They have a set of rules for analyzing and reporting problems in JavaScript files. They can be installed via npm, used from the command line by passing files, used as plugins for tools such as Grunt, or integrated into the editor. They all support configuring with comments.

But the similarities end here. Each tool has its own advantages and disadvantages - it is just that some tools have more advantages than disadvantages.

JSLint

JSLint is the oldest of these four tools. Douglas Crockford created it in 2002 with the goal of enforcing what he believes is a good part of JavaScript. If you agree with these good parts, JSLint can be a good tool – install it and use it.

The disadvantage is that JSLint is not configurable or scalable. You simply can't disable many features, and some of them are lacking documentation. The official website is not very useful, for example, it lacks any information on how to integrate it with your editor.

Pros:

• It is ready to use after configuration (if you agree to the rules it enforces).

Disadvantages:

• JSLint has no configuration file, which can become a problem if you need to change the settings.
• The number of configuration options is limited and many rules cannot be disabled.
• You cannot add custom rules.
• Function not recorded.
• It is difficult to know which rule causes which error.

JSHint

JSHint is created as an easier-to-configurable version of JSLint (which is a branch of JSLint). You can configure each rule and put them in a configuration file, which makes JSHint easy to use in large projects. JSHint also provides good documentation for each rule so you know exactly what they do. Integrating it into the editor is also simple.

A small drawback of JSHint is that it comes with a loose default configuration. This means you need to make some setup to make it work. Compared to ESLint, it is also difficult to know which rules need to be changed to enable or disable certain error messages.

Pros:

• Most settings are configurable.
• Support configuration files to make them easier to use in large projects.
• Support many libraries out of the box, such as jQuery, QUnit, NodeJS, Mocha, etc.
• Basic ES6 support.

Disadvantages:

• It is difficult to know which rule causes the error.
• has two types of options: mandatory and relaxation (can be used to make JSHint stricter or suppress its warnings). This may make the configuration slightly confusing.
• Custom rules are not supported.

JSCS

JSCS differs from other tools in that it does nothing unless you provide a configuration file or tell it to use a preset. You can download configurations from their website, so that's not a big problem, it has a lot of presets like jQuery coding style presets and Google presets.

It has over 90 different rules that you can create custom rules using plugins. JSCS also supports custom reporting programs, which makes it easier to integrate with tools that require input in a specific format.

JSCS is a code style checker. This means it only catches problems related to the code format, not potential errors. So it's not as flexible as other tools, but JSCS does the job well if you need to enforce a specific coding style.

Pros:

• Supports custom reporting programs, which can make it easier to integrate with other tools.
• Presets and ready-made configuration files can make it easier for you to set up if you follow one of the coding styles available.
• There is a flag that can include rule names in the report, so it is easy to find out which rule causes which error.
• You can extend it using custom plugins.

Disadvantages:

• Only detect code style conflicts. JSCS does not detect potential errors, such as unused variables or unexpected global variables, etc.
• The slowest of the four tools, but this is not a problem in typical use.

ESLint

ESLint is the latest of these four tools. It is designed to be easy to scale, with a lot of custom rules, and easy to install more rules in the form of plugins. It provides concise output, but contains rule names by default, so you always know which rules cause error messages.

ESLint documentation may be a bit uneven. The rule list is easy to understand and grouped into logical categories, but the configuration instructions are a bit confusing in some places. However, it does provide links to editor integrations, plugins, and examples in one place.

Pros:

• Flexible: Any rule can be switched, and many rules have additional settings that can be adjusted.
• is very extensible and has many plugins available.
• Easy to understand output.
• contains many rules not found in other code style checking tools, making ESLint more useful in detecting problems.
• The best ES6 support and the only tool to support JSX.
• Support custom reporting programs.

Disadvantages:

• Requires some configuration.
• Slow speed, but this does not prevent use.

Recommended

I chose ESLint among these four tools. JSLint is strict and unconfigurable, while JSHint lacks an extension mechanism. If you just want to check the code style, JSCS is a good choice, but ESLint can do that, and it also checks for errors and other issues in your code.

ESLint is also an obvious choice if you want to use ES6 (or ES2015 as they seem to call it so now). Of all the mentioned tools, it has the most extensive support for ES6 features.

If you want to try ESLint, I have simplified it for you by creating a 5-step quick start guide. You can download the ESLint 5-step quick start guide from my website.

JSHint is the powerful second choice. If you don't need the advanced features of ESLint, JSHint can catch a lot of problems after being properly configured. JSCS has a lot of rules available, and it is a great option if you only need code style checks (indents, braces, etc.).

I hesitate to recommend JSLint. Other tools do the same, but do not impose any specific rules on the user. The only exception is that if you happen to agree with all the rules it enforces, in which case it may be worth looking into.

Code style checking tool is a great way to find problems, but it can only find errors that its rules allow. To more reliably automatically catch errors, I recommend using unit tests. Code review can also help with this purpose.

How do you and your team ensure the quality of your code?

FAQs about JavaScript Code Style Checker Tools

(The FAQ part is omitted here because the length is too long and does not match the pseudo-original goal. The FAQ part can be added or modified as needed.)

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