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JSLint

See Also

• JS
• JS Doc Systems
• JS Formatters

Overview

http://www.jslint.com/ is a static analyzer for .js files.

• PtII Jenkins JSLint Output Until the nightly build runs, see http://terra.eecs.berkeley.edu:8080/job/ptII-test/checkstyle The JSLint output listed in Jenkns under checkstyle because the JSLint Jenkins plugin generates checkstyle compatible output.
• http://www.jslint.com/ - paste your code in and get feedback
• JSLint JavaScript Function Includes links to ways to run JSLint from a command line

JSLint is very picky, but it is worth understanding why it complains about various issues.

Sample Run

See node-jslint below for how to install

JSLint Warnings.

Running code through JSLint is rather depressing.

https://jslinterrors.com/ helps explain warnings.

Common Changes for JSLint

We are using JSLint because it is a common tool that other people will use on our code.

• If you place this code below the main comment, then you will avoid many JSLint warnings.

• "use strict" fixes "Missing 'use strict' statement."
  • https://jslinterrors.com/missing-use-strict-statement
• /*global fixes "was used before it was defined.". Note that there is no space between the /* and global
  • https://jslinterrors.com/a-was-used-before-it-was-defined

• Use function ( not function(
• Add trailing semicolons (Eclipse warns about this).
• Fix the indentation to match JSLint's desires.

JSLint and Eclipse complain about "for each"

JSLint fails to handle for each:

The Problems tab in the JavaScript Perspective of Eclipse Luna also complains:

https://wiki.openjdk.java.net/display/Nashorn/Nashorn+extensions suggests using "for of"

However, using "for of" in localFunctions.js fails in Ptolemy II:

• http://www.sitepoint.com/forums/showthread.php?646397-jsLint-complaint-about-for-each-statement - 2009 discussion about JSLint and "for each"

node-jslint

• https://github.com/reid/node-jslint - node version

It is possible to use npm install node-jslint to install node-jslint, but I could not get the command line version working, so I downloaded the git repo instead.

1. Install:
   cd $PTII/vendors
   git clone https://github.com/reid/node-jslint.git
   cd node-jslint
   make

   [$[Get Code]]
2. Run JSLint on a file:
   bash-3.2$ vendors/node-jslint/bin/jslint.js ptolemy/actor/lib/jjs/basicFunctions.js
   
   ptolemy/actor/lib/jjs/basicFunctions.js
    #1 Unexpected dangling '_' in '_debug'.
       var _debug = false; // Line 8, Pos 5
    #2 Missing 'use strict' statement.
       var MessageHandler = Java.type('ptolemy.util.MessageHandler'); // Line 13, Pos 5
    #3 'Java' was used before it was defined.
       var MessageHandler = Java.type('ptolemy.util.MessageHandler'); // Line 13, Pos 26
   
   ...

   [$[Get Code]]

node-jslint Problems

Cannot find module 'readable-stream'

Solution: Run make

Jenkins

• PtII Jenkins JSLint Output Until the nightly build runs, see http://terra.eecs.berkeley.edu:8080/job/ptII-test/checkstyle
• JSlint Jenkins Plugin Documentation

Jenkins Undefined Errors

"You'll probably find that if you use library "foo" you get a lot of "undefined foo" errors at first. Just put a globals statement at the top of your JavaScript file so jslint knows that "foo" is a global:"

"Please note: you must NOT have a space between "*" and "globals", otherwise it won't work"

Another possibility is to invoke JSLint with -Dpredef=foo,bar,baz

The Jenkins configuration states: "This would be like having /*global foo,bar,baz*/ at the top of every JavaScript file JSLint runs on."

So, we use -Dpredef=Java,actor in the Jenkins JSLint configuration.

Jenkins Problems

Jenkins output is not very descriptive

The Jenkins output does not include as much detail as running from the command line. The Jenkins output includes:

  No description available. Please upgrade to latest checkstyle version.

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