Via ZenDesk, a user reported that a timeline URL including the fragment &zoom_sequence=[0.5,1,2,3,5,8,13,21,34,55,89] did not achieve the desired effect, and, in fact, broke the zoom function.

This is one of the exceptions noted on the options documentation page, "you can pass most of these as URL parameters" (emphasis added).

At its heart is that TimelineJS accepts most options passed in the constructor as strings (see this code). There's special handling for default_bg_color, to see if it is passed as a string.

At a minimum, the Zoom function should not fail if a String value is provided for this option. It could be rejected, or, if done safely, possibly converted into a true array. (safely means no eval of course).

Of course, this option can be passed as an array if a timeline is initialized via javascript code; the issue only arises when it is passed as a URL parameter to the embed page.