如何在javascript中使用另一个函数的变量

function function1() {
  var variable = "Hello!";
  function2(variable);
}

function function2(param) {
  console.log(param);
}

function1(); // 输出：Hello!

function function1() {
  var variable = "Hello!";
  return variable;
}

function function2() {
  var value = function1();
  console.log(value);
}

function2(); // 输出：Hello!

function function1() {
  var variable = "Hello!";
  return function() {
    console.log(variable);
  };
}

var innerFunction = function1();
innerFunction(); // 输出：Hello!