可以使用此脚本更改单击事件时变量的值

var bool_val=false;
function changeVal(){
  bool_val=!bool_val;
   console.log(bool_val);
}

<input type="button" value="change" onclick="changeVal();">

一个可能的解决方案是使用localStorage保存bool值，下面是一个示例

// Your boolean is whatever you have in the localStorage if the localStorage is empty the default value will be 0
let bool = localStorage.getItem('myBoolValue') | 0; 

switchCameraButton.addEventListener('click', function() {             
    camera.switch();
    
    // this is the logical not operator it transform your bool variable from 0 to 1 and vise versa
    bool = !bool;
    
    // save your bool in localStorage, by using the + am just turning true or false to 1 or 0
    localStorage.setItem('myBoolValue', +bool);
 });

console.log(bool);

我认为你需要确保bool变量是在onclick函数之外声明的，这样bool的值就可以在函数之外访问，并且在按钮被点击时更新。
例如：

var bool = 0;

switchCameraButton.addEventListener('click', function() {
    camera.switch();
    if(bool == 0){
        bool = 1;
    }else{
        bool = 0;
    }
});

console.log(bool);