javascript - 如何将使用全局变量的递归函数转换为纯函数？

Question

我有一个程序可以对提供给它的 2 个对象进行深度比较，并使用递归来进行比较。我的问题是，因为我使用全局变量来保留信息，所以我必须在每次对该函数进行任何后续调用之前重新设置它。除了使用全局变量之外，有什么方法可以维护变量值并且不会那么麻烦吗？

let isEqual = true;
function deepEqual(object1, object2) {

  if (!((typeof(object1) == 'object' && typeof(object2) == 'object') || (object1 && object2))) {

    return isEqual = object1 === object2;

  } else if (typeof(object1) == 'object' && typeof(object2) == 'object') {

    if ((object1 && object2)) {

      let object1Keys = Object.keys(object1);

      let object2Keys = Object.keys(object2);
    
      if (object1Keys.length == object2Keys.length) {
        for (let index = 0; index < object1Keys.length; index++) {
          if (isEqual) {
            if (!(typeof(object1[object1Keys[index]]) == 'object' && typeof(object2[object2Keys[index]]) == 'object')) {
             isEqual = (object1[object1Keys[index]] === object2[object2Keys[index]]) && (object1Keys[index] === object2Keys[index]);
            } else {
              deepEqual(object1[object1Keys[index]], object2[object2Keys[index]]);
            }

          } else {
            return isEqual = false;
          }
        }
      }
    }

  }

  return isEqual;
}

let obj1 = {
  a: 'somestring',
  b: 42,
  c: {
    1: 'one',
    2: {
      4: 'Three'
    }
  }
};

let obj2 = {
  a: 'somestring',
  b: 42,
  c: {
    1: 'one',
    2: {
      3: 'Three'
    }
  }
};
console.log("obj1 == obj2 : ");
console.log(deepEqual(obj1, obj2));


let obj3 = {
  a: 'somestring',
  b: 42,
  c: {
    1: 'one',
    2: {
      3: 'Three'
    }
  }
};

let obj4 = {
  a: 'somestring',
  b: 42,
  c: {
    1: 'one',
    2: {
      3: 'Three'
    }
  }
};
console.log("obj3 == obj4 : ");
isEqual = true;
console.log(deepEqual(obj3, obj4));
let obj = {name: {gender: "F"}, age: 20};
isEqual = true;
console.log(deepEqual(obj, {name: {gender: "F"}, age: 20}));

Answer 1

你根本不需要使用它:你可以通过递归完成整个事情:

function deepEqual(o1, o2){
  if (typeof o1 != typeof o2)
    return false;

  if (typeof o1 != 'object' || o1 === null || o2 === null)
    return o1 === o2;

  for (var k in o1){
   if (!deepEqual(o1[k], o2[k]))
    return false;
  }
  for (var k in o2){
    if (!(k in o1))
      return false;
  }
  return true;
}