我们如何从外部作用域的箭头函数内部获取值？

const externalValue = 10;

const arrowFunction = (value) => {
  console.log(value);
};

arrowFunction(externalValue);  // 输出：10

const externalValue = 10;

const outerFunction = () => {
  const internalValue = externalValue;
  
  const arrowFunction = () => {
    console.log(internalValue);
  };
  
  arrowFunction();  // 输出：10
};

outerFunction();

const obj = {
  externalValue: 10,
  arrowFunction: () => {
    console.log(obj.externalValue);
  }
};

obj.arrowFunction();  // 输出：10