I don't have a source, but no, I remember hearing about them before Slack's reactions were released. What they really were is a take on ("copy of") Path's reactions[1], which are very similar in concept.
But I think putting too much importance on "copy" is wrongheaded. Facebook's team seems smart to "copy" these things from other platforms that prove their worth, just like tons of other platforms "copy" original things that Facebook's team has vetted. Who cares.
But I think putting too much importance on "copy" is wrongheaded. Facebook's team seems smart to "copy" these things from other platforms that prove their worth, just like tons of other platforms "copy" original things that Facebook's team has vetted. Who cares.
[1]: http://techcrunch.com/2015/10/08/with-reactions-facebook-sup...