Swapping two variables with only two variables

//first we define our variables
var a = "programmer"
var b = "humor"

//then put them both in a
var a = a + "_" + b
//then assign the part before the separator to b
var b = a.split("_")[0]
//lastly assign tje part after the separator to a
var a = a.split("_")[1]

//then we just output them to the document
document.write("Var A: " + a + "<br> Var B: " + b)