有没有办法确保页面刷新后变量不会改变？ [复制]答案

【问题标题】：Is there a way to make sure a variable doesn't change after a page refreshes? [duplicate]有没有办法确保页面刷新后变量不会改变？ [复制]
【发布时间】：2019-05-13 22:51:33
【问题描述】：

我正在使用随机生成的数字制作数字猜谜游戏，但是当您猜数字时，数字会发生变化，我希望它保持不变，直到数字被正确猜出。这就是代码的样子，我不明白为什么每次猜测后数字都会改变。

<!DOCTYPE html> 
<html> 
<head> 
<title>Number Guessing Game</title> 

</head> 

<body> 
<h1>Guess The Number</h1> 

<p>A number has been randomly generated from 1- 50. Please try and     guess the number.</p> 

<form> 
<label for="guessField">Enter a guess: </label> 
<input type = "text" id = "guessField" class = "guessField"> 
<input type = "submit" value = "Submit guess"
    class = "guessSubmit" id = "submitguess"> 
</form> 

<script> 
// for some reason a new random number is generated after every guess
const randomnumber = Math.floor(Math.random()*50) +1;  

var guess = 0; 

document.getElementById("submitguess").onclick = function(){ 

var userguess = document.getElementById("guessField").value; 

if(userguess<1||userguess>50||isNaN(userguess)){
guess+=1;
alert("That is not a valid guess.")
}

else if(userguess == randomnumber) 
{    
alert("You got it in "
        + guess + " guess(es) "); 
} 
else if(userguess > randomnumber) 
{    
guess+= 1; 
alert("That guess is too high. Try again!"); 
} 
else 
{ 
guess+=1; 
alert("That guess is too low. Try again!") 
} 
} 

//this shows that it changes after every guess 
document.write(randomnumber)
</script> 

</body> 
</html>

【问题讨论】：

您需要禁用刷新页面的表单提交

标签： javascript math

【解决方案1】：

将<input type="submit" .. > 更改为<button type="button" .. >。提交按钮正在提交页面并导致重新加载。

【讨论】：

【解决方案2】：

替换

<input type="submit" value="Submit guess" class="guessSubmit" id="submitguess">

与

<button type="button" class="guessSubmit" id="submitguess">Submit guess</button>

因此，当您单击按钮时，您不会收到表单提交（因此，页面重新加载会重置所有 Javascript）。

接下来，您需要将该输入字段的值转换为Number（输入字段值总是字符串）以便与数字进行比较：

var userguess = parseInt(document.getElementById("guessField").value);

【讨论】：