FireFox 2 released bragging JavaScript 1.7 but actually using 1.5?

FireFox 2 is released and can be downloaded at! What does this mean for us browser compatibility testers?

From experience, my compatibility testing woes that come with version changes are:

1. JavaScript version changes, causing JavaScript errors.
2. Rendering engine changes (especially CSS); causing display issues (e.g. object alignment, font changes/inconsistency).

So….as I peruse the FireFox 2 feature list I see an upgrade to JavaScript 1.7. Hmm, sounds historically defect prone…BUT, before I read the feature list I went and did my own homework of seeing if the JavaScript version changed. My homework unveiled that FireFox 2 was using JavaScript 1.5? WHAT THE? Am I looking at an issue caused by having multiple FireFox installations on a machine (I have 1.0.8, 1.5.4, and 2.0 installed). When you’re running FireFox 2 what is your JavaScriptVer when you visit Leave your findings in the comments please!

3 Responses to FireFox 2 released bragging JavaScript 1.7 but actually using 1.5?

  1. Phillip Forteza says:

    The box I installed FF 2.0 on already had 1.0.7 on it. My 2.0 installation went into a new directory so I could run both versions. That being said, the JavaScript version on 2.0 is just like yours, 1.5.


  2. russ says:

    same deal. Only 1.5 not 1.7

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