1. Mistakes I made #01 - Array.prototype.indexOf 20.11.2016

    Today I want to talk about a misconception about Array.prototype.indexOf I came across a few days ago. What is it doing? The indexOf() method returns the first index at which a given element can be found in the array, or -1 if it is not present. (MDN) So this is pretty simple to understand, right? … Nope! Not for me as my mistake will show you. Playing around with it So here are some examples: