This is a really tiny, stupid, simple binary search library for Node.JS. We wrote it because existing solutions were bloated and incorrect.
This version is a straight port of the Java version mentioned by Joshua Bloch in his article, Nearly All Binary Searches and Merge Sorts are Broken.
Thanks to Conrad Irwin and Michael Marino for, ironically, pointing out bugs.
var bs = require("binary-search");
bs([1, 2, 3, 4], 3, function(a, b) { return a - b; }); // => 2
bs([1, 2, 4, 5], 3, function(a, b) { return a - b; }); // => -3
Be advised that passing in a comparator function is required. Since you're probably using one for your sort function anyway, this isn't a big deal.
The 3rd and 4th arguments to the comparator are the current index and array, respectively. You shouldn't normally need the index or array to compare values, but it's there if you do.
You may also, optionally, specify an input range as the final two parameters, in case you want to limit the search to a particular range of inputs. However, be advised that this is generally a bad idea (but sometimes bad ideas are necessary).
To the extent possible by law, The Dark Sky Company, LLC has waived all copyright and related or neighboring rights to this library.