JavaScript报错：Uncaught ReferenceError: XYZ is not defined的解决方法

console.log(foo); // Uncaught ReferenceError: foo is not defined

let bar = 42;
console.log(baz); // Uncaught ReferenceError: baz is not defined

{
  let temp = 'hello';
}
console.log(temp); // Uncaught ReferenceError: temp is not defined

myFunction(); // Uncaught ReferenceError: myFunction is not defined

console.log(value); // Uncaught ReferenceError: value is not defined
let value = 10;

let foo = 'bar';
console.log(foo); // 'bar'

let bar = 42;
console.log(bar); // 42

{
  let temp = 'hello';
  console.log(temp); // 'hello'
}

function myFunction() {
  console.log('Function is defined');
}
myFunction(); // 'Function is defined'

let value = 10;
console.log(value); // 10

// 错误代码
console.log(count); // Uncaught ReferenceError: count is not defined

// 修正代码
let count = 10;
console.log(count); // 10

// 错误代码
let number = 100;
console.log(num); // Uncaught ReferenceError: num is not defined

// 修正代码
let number = 100;
console.log(number); // 100

// 错误代码
{
  let message = 'Hi';
}
console.log(message); // Uncaught ReferenceError: message is not defined

// 修正代码
{
  let message = 'Hi';
  console.log(message); // 'Hi'
}

// 错误代码
displayMessage(); // Uncaught ReferenceError: displayMessage is not defined

// 修正代码
function displayMessage() {
  console.log('Hello, world!');
}
displayMessage(); // 'Hello, world!'

// 错误代码
console.log(price); // Uncaught ReferenceError: price is not defined
let price = 50;

// 修正代码
let price = 50;
console.log(price); // 50