That is the unary plus operator. It attempts to convert the argument that follows into a number if it isn't already a number. The Date object implements a method that allows it to be converted to a number, which is the timestamp identical to the getTime() method.

That is the unary plus operator. It attempts to convert the argument that follows into a number if it isn't already a number. The Date object implements a method that allows it to be converted to a number, which is the timestamp identical to the getTime() method.

A more legible and obvious way of getting a timestamp without using an extra variable is to use parentheses:

var timestamp = (new Date()).getTime();