For e.g. Magento uses ExtJS which is under GPL v3. Now, when Magento is downloaded and installed by shopping-store-owners, you mean store-owners have to give a link to their 'whole-website-source' along with their Products ? Funny Lol
So In my opinion, a Javascript library licensed under GPL v3 is good for any project unless you are trying to modify the Javascript library and selling it commercially or related commercial-services.
