我无法让do while循环在javascript中工作

Question

Here is my code. I am trying to get it to ask 1. "What would you like to eat" and then 2. ask again if userEntree is not burger, chicken, or fish.

var userEntree = prompt('What entree would you like?')

do {
   var userEntree = prompt('What entree would you like?')
}
while(userEntree.toLowerCase() != "burger" || 
      userEntree.toLowerCase() != "chicken" || userEntree.toLowerCase() != 
      "fish") 

Answer 1

You're using the wrong operator:

(userEntree.toLowerCase() != "burger" && userEntree.toLowerCase() != "chicken" && userEntree.toLowerCase() != "fish")

"Do something until the user's answer is chicken or burger or fish" translates into a while-condition as "Do something while the answer is not chicken and not burger and not fish."

Also, the first var userEntree = prompt('What entree would you like?') is unnecessary; this way, the code will always prompt at least twice. You should either declare userEntree as null , or write the loop as a while loop instead of do-while .