Result of `document.getElementsByClassName` doesn't have array methods like `map` defined, even though it is an array
Right, it's not really an array. It's an "array-like".
Don't attach map to tiles. Just do
Array.prototype.map.call(tiles, function...)Some might suggest
Array.prototype.slice.call(tiles).map(function...which sort of boils down to the same thing. There are those who prefer to write
[].slice.call(tiles).map(function...which saves a few keystrokes.
Of course, since you're not really using map to return an array, you could loop in the old-fashioned way:
for (var i = 0; i < tiles.length; i++) { tiles[i].addEventListener("click", function(e){ console.log("click!"); });}See also explanation at MDN. Although this discusses NodeList, the same principles apply to HTMLCollection, which is what getElementsByClassName returns.
In ES6, we have some easier ways to turn tiles into an array, including
[...tiles]Array.from(tiles)