如何提示直到條件滿足？

Question

我試圖提示用戶，直到輸入等於數組中的元素之一？

do {
      var bestCities = ["miami","sanfrancisco","austin","chicago","phoenix"]
      var userInput = prompt('Whats your city?');
    } while (
        userInput !== bestCities[i]
      );
    alert('I love ' + i + ' also' );

Answer 1

可能：

 var bestCities = ["miami","sanfrancisco","austin","chicago","phoenix"]; var userInput; do{ userInput = prompt('Whats your city?') } while (bestCities.indexOf(userInput) === -1); alert('I love ' + userInput + ' also' ) 

indexOf（）返回數組的位置。

未找到匹配項時， indexOf返回-1 。 因此，當找到-1以外的索引時，循環結束。 例如， miami處於0位置， chicago處於3位置。

Answer 2

這是一個更好的架構：

var validCity = false;

while(!validCity) {
    var input = prompt("What is your city");
    if(bestCities.indexOf(input) != -1) validCity = true;
}

Answer 3

do {
      var bestCities = ["miami","sanfrancisco","austin","chicago","phoenix"]
      var userInput = prompt('Whats your city?');
    } 
while (bestCities.indexOf(userInput)==-1);
alert('I love ' + userInput  + ' also' );

只需檢查數組索引即可解決問題

Answer 4

一個更好的方法：

const bestCities = ["miami", "sanfrancisco", "austin", "chicago", "phoenix"];
let userInput;
do {
  userInput = prompt("Whats your city?");
} while (!bestCities.includes(userInput));
alert(`I love ${userInput} also`);

注意：這只是對當前最熱門答案的改進。