By John Gruber
Square Reader SDK lets you use Square hardware to take payments in your app.
I’ve been experimenting with the use of footnotes here on Daring Fireball over the last few months.1 In print, implementing footnotes is rather straightforward: put the note references in the text, then place the notes themselves in smaller type at the bottom of the pages where the references occur.
In a weblog post, the implementation is not so obvious. It’s easy to just put the note references in the text, in superscript, and make them clickable links that jump to the notes themselves at the bottom of the article. And that’s more or less all I did, originally.
The problem with this is that a weblog post — especially longish ones like those here at Daring Fireball — is very different from a printed page in a book. When you, i.e. the reader, encounter a footnote reference in a book, you can glance down to the bottom of the current page to read the note, then glance back up to your original position in the text. You can do this because you have some short-term spatial memory of where the footnote reference was — and all you have to do is get close, visually, and your eyes will quickly spot the superscript footnote reference.
But with a weblog post, there are no “pages”. It’s just one long article that scrolls down continuously. By placing the notes at the bottom of the article, they’re in some way more like endnotes than footnotes. Assuming there’s a hyperlink from the superscript footnote reference to the note itself, how do you get back to where you were when you’re done reading the note?
It ends up you can use the browser Back button for this, but this isn’t obvious, and it isn’t perfect. Because what if you (again, the reader) decide to wait and read the notes after you’ve finished the article, rather than reading them on-the-fly as you encounter the references? It’d be nice to be able to figure out from the notes themselves where they were referenced in the text.
So, here’s what I’ve come up with.
At the end of each footnote, I’ve included a link back to the spot in the text where the note is referenced. Rather than add needless noise to the page, instead of using a textual link, I’m simply using a bit of Unicode typography:
A.k.a. Unicode LEFTWARDS ARROW WITH HOOK, decimal-encoded HTML
↩. Clicking on the arrow at the end of each note will
jump you back to the spot in the text where the note was referenced.
This works pretty well and looks pretty good, and it solves the “how
do you get back to the text from the footnote” problem concisely and
There are innumerable other ways footnotes — or footnote-esque asides — can be implemented on the web. Dynamic HTML techniques allow you to toggle element visibility on the fly. I considered ideas for displaying footnotes to the right of the main text column, and also making them pop into place directly underneath the paragraph in which they’re referenced. I’ve seen some sites which implement footnote-esque asides as mouseover tooltips.