for (var k = 0; k < original.length; k++)
                {
                    original[k].normal && allowed.push(original[k]);
                }

Could anyone explain what the programmer is doing here. I read it as cycling through an array and pushing those elements into a new array called allowed. but I have never come across && used in this way. I could only see the relevance of doing something this way, if it was looking for the opportunity to break it if there was not a original[k].normal.

I am not that familiar to html5 javascript, so if someone could give me a literal translation of what that line is trying to say.