shallow copy vs deep copy javascript code example

Example 1: copy object javascript

var x = {key: 'value'}
var y = JSON.parse(JSON.stringify(x))

//this method actually creates a reference-free version of the object, unlike the other methods
//If you do not use Dates, functions, undefined, regExp or Infinity within your object

Example 2: js shallow copy

Object.assign({}, obj); // ES6 shallow copy

Example 3: javascript '=' operator shallow copy or deep copy

// The '=' operator in javascript can serve the purpose of shallow vs
// deep copy.

// The '=' operator in javascript will assign deep copy to primitive 
// data types. For example:
let a = 10;
let b = a;
b = 4;
console.log(a);
// Output: 10
console.log(b);
// Output: 4


// The '=' operator in javascript will assign shallow copies to
// non-primitive data types. For example:
let a = ['a','b','c','d','e','f','g'];
let b = a;
b.pop();
console.log(a);
// Output: ["a","b","c","d","e","f"]
console.log(b);
// Output: ["a","b","c","d","e","f"]

Example 4: shallow copy vs deep copy js

/*

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A deep copy means that all of the values of the new variable
are copied and disconnected from the original variable. 
A shallow copy means that certain (sub-)values are still connected
to the original variable. To really understand copying,
you have to get into how JavaScript stores values


/*

Example 5: best way to clone an object in javascript

const person = {
    firstName: 'John',
    lastName: 'Doe'
};


// using spread ...
let p1 = {
    ...person
};

// using  Object.assign() method
let p2 = Object.assign({}, person);

// using JSON
let p3 = JSON.parse(JSON.stringify(person));