JavaScript_Succinctly

console.log(FooInstance.constructor === Foo); // Logs false, we broke the
reference.
console.log(FooInstance.constructor); // Logs Object(), not Foo()
// Compare to code in which we do not replace the prototype value.
var Bar = function Bar() { };
var BarInstance = new Bar();
console.log(BarInstance.constructor === Bar); // Logs true.
console.log(BarInstance.constructor); // Logs Bar()
If you intend to replace the default prototype property (common with some JS OOP
patterns) set up by JavaScript, you should wire back together a constructor property
that references the constructor function. In the following sample, we alter our previous
code so that the constructor property will again provide a reference to the proper
constructor function.
Sample: sample126.html
var Foo = function Foo() { };
Foo.prototype = { constructor: Foo };
var FooInstance = new Foo();
console.log(FooInstance.constructor === Foo); // Logs true.
console.log(FooInstance.constructor); // Logs Foo()
Instances that inherit properties from prototype will always get the
latest values
The prototype property is dynamic in the sense that instances will always get the latest
value from the prototype regardless of when it was instantiated, changed, or appended.
In the code that follows, we create a Foo constructor, add the property x to the
prototype, and then create an instance of Foo() named FooInstance. Next, we log
the value of x. Then we update the prototype’s value of x and log it again to find that our
instance has access to the latest value found in the prototype object.
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