By default Magento 2 static urls have a version string attached to it. For example, if you take the view source of the page, you will see urls contains the following string -version1490119662. That’s called versioning for the static assets. In developer mode when we clear the cache this change automatically.
You can disable versions with two methods
From core_config_data table set ‘dev/static/sign‘ to 0
From admin side graphic interface.
Admin -> Stores -> Configuration -> Advanced -> Developer -> Static Files Settings Set ‘Sign Static Files’ to ‘No’