Difference between __proto__ and Prototype in JavaScript | Well explained | Astute Js
https://jsfiddle.net/sathishkrcs/67q6...
prototype is a property of a Function object. It is the prototype of objects constructed by that function.
_proto_ is internal property of an object, pointing to its prototype. Current standards provide an equivalent Object.getPrototypeOf(O) method, though de facto standard _proto_ is quicker.
You can find instanceof relationships by comparing a function's prototype to an object's _proto_ chain, and you can break these relationships by changing prototype.
https://stackoverflow.com/questions/9...