JavaScript，一个用于询问特定答案的循环

Question

我希望用户输入一个 1-100 之间的数字，直到用户输入一个有效数字，循环会一直说“该输入无效”。

我的代码如下。我哪里出错了？

// Initialize var userGuess
var userGuess;

// I want to make the prompt keep asking a number between 1-100, if it doesn't satisfy the requirement, it will keep asking
for (var valid = false; valid == true;) {
    userGuess = prompt("Guess a number");
    if ((userGuess >= 1) && (userGuess <= 100)) {
        valid = true;
    } else {
        valid = false;
        console.log("That number is invalid! Please enter a number between 1-100");
    }
}

Answer 1

// Initialize var userGuess
var userGuess;

// I want to make the prompt keep asking a number between 1-100, if it doesn't satisfy the requirement, it will keep asking
var valid = false;
while(!valid){
    userGuess = prompt("Guess a number");
    if ((userGuess >= 1) && (userGuess <= 100)) {
        valid = true;
    } else {
        console.log("That number is invalid! Please enter a number between 1-100");
    }
}


// Initialize var userGuess
var userGuess;

用for循环

// I want to make the prompt keep asking a number between 1-100, if it doesn't satisfy the requirement, it will keep asking
for(var valid = false; !valid){
    userGuess = prompt("Guess a number");
    if ((userGuess >= 1) && (userGuess <= 100)) {
        valid = true;
    } else {
        console.log("That number is invalid! Please enter a number between 1-100");
    }
}