A Beginners Guide to Using JSLint


This is a blog about the awesomeness of JSLint.

JSLint is a JavaScript program that looks for problems in JavaScript programs. It is a code quality tool.

JSLint takes a JavaScript source and scans it. If it finds a problem, it returns a message describing the problem and an approximate location within the source. The problem is not necessarily a syntax error, although it often is. JSLint looks at some style conventions as well as structural problems. It does not prove that your program is correct. It just provides another set of eyes to help spot problems.

This is a blog about the awesomeness of JSLint, a program written by Douglas Crockford that statically analyzes your code and checks it against his rules for what constitutes good JavaScript programming style.

As a side note, this will be a beginner’s guide to JSLint, targeted at people who have no previous experience with it. Additionally, this will be from a Front End Developer’s perspective (although much of the information contained in this blog post can be applied to other situations).

Why Use JSLint?

JSLint is good for your code because it allows you to write code that is more consistent and also more efficient. These two things are important because they allow other developers to understand what you wrote faster and more easily, thus making your code easier to maintain.

A Beginners Guide to Using JSLint”

So you’ve heard about this amazing JavaScript linting tool called JSLint. You’ve seen it used in other peoples demos, but weren’t sure how to go about setting it up and using it on your own projects. This article will take you through a few simple steps that will show you how easy it is to start using JSLint.

Minified JavaScript files are hard to read and maintain. To avoid this, many people practice a style of development where they first write their code in an uncompressed format, then compress that into a minified file for use on the web. While this strategy makes your JavaScript files easier to read and maintain, there is another problem you may run into. If your uncompressed source contains errors or bad practices, those same issues will be carried over into the compressed version of your script. This is where JSLint can help us out! It will check our source for any problems before we compress it!

JSLint is a JavaScript program that looks for problems in JavaScript programs. It is a code quality tool.

JSLint takes a JavaScript source and scans it. If it finds a problem, it returns a message describing the problem and an approximate location within the source. The problem is not necessarily a syntax error, although it often is. JSLint looks at some style conventions as well as structural problems. It does not prove that your program is correct. It just provides another set of eyes to help spot problems.

The more time you spend thinking about the rules, the more you will get out of JSLint. JSLint will hurt your feelings.

I’ve been using JSLint to help me write better Javascript for a while now. This is a tool provided by Douglas Crockford that lets you validate your Javascript and even more importantly helps educate you on writing better Javascript.

I can’t recommend it enough.

There are a few quirks about JSLint that make it a bit difficult to use for beginners though:

The website is a bit daunting. It’s just one big text box with options below it. It looks like the kind of thing only an expert would know how to use, but it’s not really.

It doesn’t give you any meaningful errors or warnings if you do something wrong in your code; just a cryptic message like: “Problem at line 12 character 5: Expected ‘{‘ and instead saw ‘something’.”

You have to manually tell JSLint which version of Javascript to validate against (for example, 1.6 or 2.0). If you don’t do this it simply won’t work for some reason.

All of these problems can be overcome with a little effort though, so here’s what I recommend:

The best way to understand JSLint is to just use it. It will help clean up your code, make you a better programmer and quite possibly save you from hours of debugging hell.

JSLint takes a JavaScript source and scans it. If it finds a problem, it returns a message describing the problem and an approximate location within the source. The problem is not necessarily a syntax error, although it often is. JSLint looks at some style conventions as well as structural problems. It does not prove that your program is correct. It just provides another set of eyes to help spot problems.

JSLint is a JavaScript program that looks for problems in JavaScript programs. It is a code quality tool.

If you are already using JSLint, you might find my book on JSLint helpful: “JavaScript Allongé”. My book explains the ideas behind JSLint and how to use them to improve your programs.

JSLint takes a JavaScript source and scans it. If it finds a problem, it returns a message describing the problem and an approximate location within the source. The problem is not necessarily a syntax error, although it often is. JSLint looks at some style conventions as well as structural problems. It does not prove that your program is correct. It just provides another set of eyes to help spot problems.


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