How many ways to copy object?

Shallow Copy Methods:

1. Object.assign()

   const copied = Object.assign({}, original);

   Copies enumerable own properties from source objects to a target object. Doesn't copy prototype chain or nested objects.

2. Spread Operator

   const copied = { ...original };

   Modern syntax for shallow cloning, equivalent to Object.assign().

3. Array.prototype.slice()

   const copiedArray = originalArray.slice();

   Array-specific shallow copy method.

4. Array.prototype.concat()

   const copiedArray = [].concat(originalArray);

   Alternative array shallow copy method.

5. Manual Property Copy

   const copied = {};
   for (const key in original) {
     if (original.hasOwnProperty(key)) {
       copied[key] = original[key];
     }
   }

Deep Copy Methods:

1. JSON.parse(JSON.stringify())

   const deepCopied = JSON.parse(JSON.stringify(original));

   Serialization-based approach. Loses:

   • Functions
   • undefined
   • Symbol properties
   • Circular references
   • Special objects like Date, RegExp

2. structuredClone()

   const deepCopied = structuredClone(original);

   Native method (ES2022+) that handles:

   • Circular references
   • Date, RegExp, Map, Set, etc.
   • Preserves data types better than JSON methods

3. Lodash _.cloneDeep()

   const deepCopied = _.cloneDeep(original);

   Library implementation with comprehensive type handling.

4. Recursive Copy Function

   function deepClone(obj, hash = new WeakMap()) {
     if (obj === null || typeof obj !== 'object') return obj;
     if (hash.has(obj)) return hash.get(obj);
     
     let clone = new obj.constructor();
     hash.set(obj, clone);
     
     for (const key in obj) {
       if (obj.hasOwnProperty(key)) {
         clone[key] = deepClone(obj[key], hash);
       }
     }
     return clone;
   }

Hi Dashrath,

We can use below methods,

1. Deep copying
   • Use structuredClone() (latest)
   •  _.cloneDeep() (best library)
   • $.extend(true, ...) (if using jQuery)
2. Shallow copies
   • Use { ...obj } 
   • Object.assign()

In JavaScript and jQuery, there are several ways to copy objects. Here are some common methods:

JavaScript

1. Using Object.assign():

   const original = { a: 1, b: 2 };
   const copy = Object.assign({}, original);
   

2. Using the Spread Operator:

   const original = { a: 1, b: 2 };
   const copy = { ...original };
   

3. Using JSON methods (for deep copy, but only for JSON-compatible objects):

   const original = { a: 1, b: { c: 2 } };
   const copy = JSON.parse(JSON.stringify(original));
   

jQuery

1. Using jQuery's $.extend():

   const original = { a: 1, b: 2 };
   const copy = $.extend({}, original);
   

2. Deep copy with $.extend():

   const original = { a: 1, b: { c: 2 } };
   const copy = $.extend(true, {}, original);