JavaScript_Succinctly

console.log(cody.name); // Undefined. The value is actually set at
window.name
console.log(window.name); // Logs 'Cody Lindley'.
The keyword this inside a prototype method refers to a constructor
instance
When used in functions added to a constructor’s prototype property, this refers to the
instance on which the method is invoked. Say we have a custom Person() constructor
function. As a parameter, it requires the person’s full name. In case we need to access
the full name of the person, we add a whatIsMyFullName method to the
Person.prototype so that all Person instances inherit the method. When using this,
the method can refer to the instance invoking it (and thus its properties).
Here I demonstrate the creation of two Person objects (cody and lisa) and the
inherited whatIsMyFullName method that contains the this keyword to access the
instance.
Sample: sample109.html
var Person = function (x) {
if (x) { this.fullName = x };
};
Person.prototype.whatIsMyFullName = function () {
return this.fullName; // 'this' refers to the instance created from
Person()
}
var cody = new Person('cody lindley');
var lisa = new Person('lisa lindley');
// Call the inherited whatIsMyFullName method, which uses this to refer
to the instance.
console.log(cody.whatIsMyFullName(), lisa.whatIsMyFullName());
/* The prototype chain is still in effect, so if the instance does not
have a fullName property, it will look for it in the prototype chain. Next,
we add a fullName property to both the Person prototype and the Object
prototype. See the notes that follow this sample. */
Object.prototype.fullName = 'John Doe';
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