How do I create a frequency table with empty categories in R?

Question

I have a table with responses to multiple items in a survey. (e.g. 1 = disagree and 7 agree)

var1 <- c(2, 2, 4, 1, 5, 3, 4, 6, 7, 7, 6)
var2 <- c(3, 4, 5, 1