Question

impress.js is a new web presentation written using Javascript. I want to create custom events to go to the next page. For example, I might create a “Next” and “Previous” button.

The entire impress.js file is a function, calling selectPrev(); from within the function will go to the next page. However, I’m not very good with Javascript, I don’t know how to call selectPrev(); from outside the function.

The file can be found here: https://github.com/bartaz/impress.js/blob/master/js/impress.js

Answer 1

By the looks of it, the whole file is inside a closure, and selectNext is local to that closure. Additionally, it is only used indirectly in the key listener, so getting it from there is also impractical.

Thus, without modifying the source, I do not see any easy way to get at selectPrev/selectNext.

Here is the message from a commit about six hours ago:

impressive refactoring of slide selection - getting closer to API

It seems the developer is planning to add a proper API soon. If you wait a little, there should be some standard, sanctioned and (hopefully) documented way to interact with impress.js programatically.

If you just want a quick hack, you could always have your button trigger a key event. If you’re using jQuery, you can do it like this:

$(document).trigger($.Event("keydown", { keyCode: 38 }))

38 will go to the next slide and 40 to the previous.