Node.js //我想让函数等待一个变量，直到它运行

function waitForVariable(callback) {
  // 模拟异步操作
  setTimeout(function() {
    var variable = "Hello, World!";
    callback(variable);
  }, 1000);
}

waitForVariable(function(result) {
  console.log(result);
});

function waitForVariable() {
  return new Promise(function(resolve, reject) {
    // 模拟异步操作
    setTimeout(function() {
      var variable = "Hello, World!";
      resolve(variable);
    }, 1000);
  });
}

waitForVariable().then(function(result) {
  console.log(result);
});

async function waitForVariable() {
  // 模拟异步操作
  await new Promise(function(resolve) {
    setTimeout(resolve, 1000);
  });

  var variable = "Hello, World!";
  return variable;
}

(async function() {
  var result = await waitForVariable();
  console.log(result);
})();