When adding additional properties to a constructor, is it better to use constructorName.nameofProperty or constructorName.prototype.nameofProperty? And what are the differences between the two approaches?
When adding additional properties to a constructor, is it better to use constructorName.nameofProperty or constructorName.prototype.nameofProperty? And what are the differences between the two approaches?
Upon examining the console output of the code snippet below, you will notice that when something is added to an object's prototype it affects all instances of the constructor. In this case, both Jill and Tim now have a method called setAge, but only Jill has actually utilized it to set her age. Any additions made directly to the constructor do not get inherited by its instances.
function Person(firstName, lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
var Tim = new Person("Tim", "Dawson");
var Jill = new Person("Jill", "Swanson");
Person.prototype.setAge = function(age) {
this.age = age;
}
Jill.setAge(28);
Person.doesThisInherit = function() {
console.log("No it doesn't");
}
var Sam = new Person("Sam", "Testy");
console.log(Tim);
console.log(Jill);
console.log(Sam);It really comes down to what you're looking to achieve.
If you want the object created by the constructor function to have specific properties, then you'll need to add those properties directly to the object:
var constructorFunction = function () {
this.someProperty = someValue;
}
Alternatively, if you're wanting to add properties to the constructor function itself, you can do so as follows:
constructorName.someProperty = someValue
However, it's important to note that this will only affect the function and not the objects created from it.
If you'd like all objects created with that function to share a common property without consuming extra memory, you can attach the property to the prototype. This way, each object will reference the same property through the prototype chain. On the other hand, if memory usage is not a concern, assigning individual properties to each object (as shown in the first example) may be more appropriate. This ensures that changes made to one object's property won't impact others created by the constructor function.
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