Prototypal inheritance gotcha in JavaScript - http://mistakes.io/#5999460

prototypal-inheritance-gotcha.js

// Prototypal inheritance gotcha

var myProto = {
  prop1: 'foo',
  prop2: {
    name: 'bar'
  }
}

var obj1 = Object.create(myProto);
var obj2 = Object.create(myProto);

// Property mutation only affects instance
obj1.prop1 = 'bar';

// Array or object mutation affects prototype
obj1.prop2.name = 'foo';

obj2.prop1; //=> 'foo'
obj2.prop2.name; //=> 'foo'

// Property mutation only affects instance
obj1.prop2 = { name: 'bar' };

obj1.prop2.name; //=> 'bar'
obj2.prop2.name; //=> 'foo'