Evil sum and average of a JavaScript array

It's a hack and you shouldn't use it, but you can use only one line to sum all the values in a JavaScript array.

var sum = eval(arrayToSum.join('+'));

Basically, this creates a string expression of all of the array values added up (eg, 1+2+3) and then evaluates it with eval. Note that using eval is evil if you're not sure what's being passed in -- bad things could happen!

You can also use this to calculate an average, which was how I discovered this method:

var average = eval(arrayToAverage.join('+')) / arrayToAverage.length;