检查输入变量对阵列

Question

尝试检查输入变量（sGuess）对我的数组（sportsArray）...

var名称正常

然后当我检查用户针对数组输入的变量（sGuess）时（sportsArray）我总是在控制台中得到以下内容。 循环1返回NaN 循环2返回undefined 循环3完美地返回它的输入

我使用以下javascript代码

  var sportsArray = new Array("Football", "Basketball", "Rollerblading", "Hiking", "Biking", "Swimming");
  var name;
  var score;
  var loops;
  var sGuess;

// prompts for user name, checks input.
do {
name = prompt("Enter your first name");
}

while (name == "");


// loop for guesses.
for (var i = 1; i <4; i++) {

// prompts user for guess.
sGuess = prompt("Enter your sports guess");


if(sportsArray.indexOf(sGuess) == -1) {

    alert("Sorry! Guess Again.");
    score -= 5;
}

else {
    alert("You are good, try it again!");
    score += 5;
}
 }

如何修复循环1＆amp; 2返回错误？