[JS] Deep Equality checking of Two Objects

JSON.stringify 을 사용하지 않고 두 Object가 같은지 비교(deep-equal)

 

 

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Deep Equality checking of Two Objects

function compareObjectsDeepEqual(original, target) {
  const isObject = obj => typeof obj === "object" && obj !== null;

  if (!isObject(original) || !isObject(target)) {
    return original === target;
  }

  const keysOfOriginal = Object.keys(original);
  const keysOfTarget = Object.keys(target);

  if (keysOfOriginal.length !== keysOfTarget.length) {
    return false;
  }

  for (let key of keysOfOriginal) {
    if (!keysOfTarget.includes(key)) {
      return false;
    }

    if (isObject(original[key])) {
      if (!compareObjectsDeepEqual(original[key], target[key])) {
        return false;
      }
    } else {
      if (original[key] !== target[key]) {
        return false;
      }
    }
  }

  return true;
}

 

 

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🔽 테스트 케이스들

1. empty : const original = {}, target = {} ▶ true

2. falsy value : const original = { name: "" }, target = { name: 0 } ▶ false

3. nested ▶ true

   const original = {
     name: "Judy",
     work: {
       company: "zootopia",
       since: { year: 2017, month: 1, day: 1 },
     },
   };
   const target = {
     name: "Judy",
     work: {
       company: "zootopia",
       since: { year: 2017, month: 1, day: 1 },
     },
   };

4. null : const original = { name: null }, target = { name: null }) ▶ true

5. Array : ▶ true

   const original = { name: "Judy", array: ["0", "1", "2"] };
   const target = { name: "Judy", array: ["0", "1", "2"] };

6. Array + Type of value ▶ false

   const original = { name: "Judy", array: ["0", "1", "2"] };
   const target = { name: "Judy", array: [0, 1, 2] };

7. Do not check for a property in the object's prototype chain ▶ false

   Object.prototype.test = "Don't check me!";
   
   const original = { name: "Judy", test: "Don't check me!" };
   const target = { name: "Judy" };

8. Complex nested object + array ▶ true

   const original = {
    name: "Judy",
    array: [{ A: "apple", B: ["beer", "blue"] }],
    string: "STRING ",
   };
   const target = {
    name: "Judy",
    array: [{ A: "apple", B: ["beer", "blue"] }],
    string: "STRING ",
   };

9. Order of original and target (Two-way)
   const original = original, target) ▶ false
   const original = target, original) ▶ false

   const original = {
     A: "apple",
     B: ["beer", "blue"],
   };
   const target = {
     A: "apple",
   };