JSFiddle - React, Tailwind, and code Playground

JavaScript

if (!('copy' in Array.prototype)) {
    Array.prototype.copy = function() {
      return this.slice(0);
    }
}

var arr = [1, 2, 3, 4, 5]

var arr2 = arr.copy();

console.log(arr2)

arr = [4, 5, 56, 6]

console.log(arr2);

    if (!('copy' in Object.prototype)) {
      Object.prototype.copy = function() {
        return JSON.parse(JSON.stringify(this));
      }
    }
                          
                          var obj = { name: 'andy' }
                          var obj2 = obj.copy();
          obj.name = 'bob';
          console.log(obj2)