Saving Console Messages in JavaScript

Have you ever encountered a situation where it would be beneficial to save whatever is written to the console across browser sessions?  If you have, you know there are not many solutions.  I recently decided that localStorage would be a good candidate to implement a solution to this problem with.


logsaver.js is a lightweight, simple log preservation script.  It utilizes the flexibility of JavaScript to replace the default console.log function with a new, customized one.  Along with writing messages to the original console.log, this custom console.log  also writes messages to the specified localStorage key.

  • To start saving console.log messages, call startSavingLog().
  • To stop saving console.log messages, call stopSavingLog().
  • To clear saved console.log messages, call clearSavedLog().
  • To completely remove the localStorage key used by logsaver, call removeSavedLog().

For more information on options and how to use them, checkout the readme.

While you can copy the source below, I strongly recommend grabbing the latest from github here: logsaver.js.


  • It doesn’t handle objects well.  Results in [Object object] appearing in the localStorage key value.  This is because localStorage is limited to strings.
  • It is possible to exceed the maximum space allocated to you in localStorage.  For desktop browsers, Chrome and Firefox have a 10 MB limit, while Safari and IE both have a 5 MB limit.  These number differs for mobile browsers.  More details.  In this event, logsaver.js will stop trying to save the log and display additional error messages in the console.

v0.1.0 Source

Posted by Chad Dotson

A small town Computer Scientist / Software Engineer. Chad enjoys writing Python and JavaScript as well as tinkering with his Raspberry Pi and Arduino. When not programming, he enjoys Photography (especially lightning) and Sci-Fi.

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