Javascript Code Review Checklist

A checklist specific to doing code reviews for javascript based projects.

General

• Does the code work? Does it perform its intended function, the logic is correct etc.
• Is all the code easily understood?
• Does it conform to your agreed coding conventions? These will usually cover location of braces, variable and function names, line length, indentations, formatting, and comments.
• Is the code DRY?
• Is the code as modular as possible?
• Can any global variables be replaced?
• Is there any commented out code? (No need to leave in commented out code with source control)
• Do loops have a set length and correct termination conditions?
• Can any of the code be replaced with library functions? (Lodash, Underscore, jQuery, etc.)
• Can any logging or debugging code be removed?
• Does logging code need to be added? (error checking and handling)

Coding Best Practices

Google's JavaScript Style Guide

Airbnb JavaScript Style Guide

Security

OWASP Code Review Guide

• Are all data inputs checked (for the correct type, length, format, and range) and encoded?
• Where third-party utilities are used, are returning errors being caught?
• Are output values checked and encoded?
• Are invalid parameter values handled?

Performance

Documentation

• Do comments exist and describe the intent of the code?
• Are all functions commented?
• Is any unusual behavior or edge-case handling described?
• Is the use and function of third-party libraries documented?
• Are data structures and units of measurement explained?
• Is there any incomplete code? If so, should it be removed or flagged with a suitable marker like ‘TODO’?

Testing

• Is the code testable? i.e. don’t add too many or hide dependencies, unable to initialize objects, test frameworks can use methods etc.
• Do tests exist and are they comprehensive? i.e. has at least your agreed on code coverage.
• Do unit tests actually test that the code is performing the intended functionality?
• Are arrays checked for ‘out-of-bound’ errors?
• Could any test code be replaced with the use of an existing API?

ES6/7

• const or let used, instead of var

References

Stop More Bugs with our Code Review Checklist