Really? I'm not a JavaScript dev but this is pretty inscrutable. I think its totally reasonable for devs to expect not to have to do all this byzantine casting

Really? I'm not a JavaScript dev but this is pretty inscrutable. I think its totally reasonable for devs to expect not to have to do all this byzantine casting and comparisons just to find out if a variable contains a number. You're right in the sense that an experienced dev should know to vendor this or reimplement in code they control rather than downloading it every time they build, but the necessity of this library is more of a damnation of the JS stdlib than anything.