Answer 1

prototype is a function of a object or node
Node.prototype.nameOfFunction = function() {
alert(this.value);
}
document.getElementsByTagName("input")[0].nameOfFunction(); // to use this prototypeyou must get a input and use a method nameOfFunction. this code return value of input
var obj = {
age : 30
}
obj.prototype.nameoffunction = function() {
alert(this.age);
}
obj.nameoffunction();//use a method nameoffunction and It return obj.age ( 30 )