epam-short-track

Task 3. Deep-copy

Folder Name	Branch	Coefficient
/deep-copy	deep-copy	0.5

Task Description

Implement a custom copy function that creates a deep copy of a given object. Your implementation must handle all types listed below, support any level of nesting, and strictly follow the requirements.

Requirements

• Do not use rest/spread operators (...), structuredClone, JSON.stringify, JSON.parse, or any npm libraries.
• The function must perform a true deep copy: all nested objects and arrays must be recursively copied.
• All types must be handled:
  • Basic types: string, number, boolean, null, undefined, BigInt
  • Special types: Date, functions, arrays, objects, get/set accessors
• Keys must be strings. Keys and values must not be Symbols.
• Any property value can be null or undefined.
• The function must correctly copy objects with any nesting level.
• The solution must not mutate the original object.
• The code must be clean, readable, and follow best practices.

Example

const complexObject = {
  stringValue: "Hello, World!",
  numberValue: 42,
  booleanValue: true,
  nullValue: null,
  undefinedValue: undefined,
  bigIntValue: BigInt(9007199254740991),
  arrayValue: [1, 2, 3, "four", { nestedKey: "nestedValue" }],
  valueDate: new Date(),
  nestedObject: {
    level1: {
      level2: {
        level3: {
          stringValue: "Deep Nesting",
          numberValue: 3.14,
          booleanValue: false,
          arrayValue: [true, false, null],
          anotherNestedObject: {
            level4: "Final Level",
            functionValue: function() {
              return "I am a function!";
            }
          }
        }
      }
    }
  },
  functionValue: function() {
    return "I am a function!";
  }
};

const obj1 = copy(complexObject);

console.log(obj1 === complexObject); // false
console.log(obj1.nestedObject.level1.level2.level3 === complexObject.nestedObject.level1.level2.level3); // false
console.log(obj1.arrayValue === complexObject.arrayValue); // false

Implementation Details

• Your index.js file in the deep-copy folder must export the copy function as follows:

function copy(obj) {}

module.exports = { copy };

• Test your function locally with various objects, including the example above, before submitting your Pull Request.

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Pull Request Requirements

Your Pull Request must include:

• Task URL.
• Description of the types and structures of objects used for verification (with examples).
• Submission Date / Deadline Date.
• Your self-check of the task’s completion using checkboxes.

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Mentor Checklist

Maximum Score: 100 points

Criteria	Points
The branch is named deep-copy	2
Commit messages follow RS School Git Convention	5
The deep-copy folder exists	2
The index.js file exists in the correct folder	2
The index.js file exports the copy function	1
The function correctly deep-copies the following types:
String	5
Number	5
Boolean	5
Null	5
Undefined	5
BigInt	5
Date	8
Function	8
Array	8
Object	8
get/set accessors	8
The solution is well-structured, readable, and follows best practices	10
Pull Request description includes all required elements:
Task URL is included in the PR	2
Description of test objects and types is included in the PR	2
Submission and Deadline Dates are included in the PR	2
Your self-check of the task’s completion using checkboxes is included in the PR	2
Penalty:
Less than 3 commits in the PR	-20
Commit after the deadline and before mentor review	-20
The solution includes any comments	-50
The solution includes console.log	-10
The PR includes more than one required index.js file	-50
The solution includes rest/spread operators (...), structuredClone, JSON.stringify, JSON.parse, or any npm libraries.	-100

Notes

• The solution must be well-structured, readable, and follow best practices.
• If any required element is missing or incorrect, points will be deducted accordingly.
• All requirements regarding forbidden methods and types must be strictly followed.

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