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8. Function Prototype Property > Replacing the prototype Property with a New Ob...
Replacing the prototype Property with a New Object Removes the Default Constructor Property
It’s possible to replace the default value of a prototype property with a new value. Doing so,
however, will eliminate the default constructor
property found in the “pre-made” prototype object—unless you manually specify
one.
In the code below, we create a Foo constructor function, replace the prototype property with a new empty object, and
verify that the constructor property is broken (it now references the less
useful Object() constructor).
<!DOCTYPE html><html lang="en"><body><script>
var Foo = function Foo(){};
Foo.prototype = {}; // replace prototype property with an empty object
var FooInstance = new Foo();
console.log(FooInstance.constructor === Foo); /* logs false,
we broke the reference */
console.log(FooInstance.constructor); // logs Object(), not Foo()
// compare to code where 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()
</script></body></html>
