Adding Properties to existing Javascript Objects from Object Constructors





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When creating an object constructor in Javascript, I understand that it's necessary to prepend property names with the 'this' keyword.



function funcConstruct(first,last,age) {

        this.firstName = first;

        this.lastName = last;

        this.age = age;

        this.fullNameAge = function() {

            return this.lastName + ', ' + this.firstName + ', ' + this.age

        };

};





var johnDoe = new funcConstruct('John', 'Doe', 52);

console.log(johnDoe.fullNameAge()); 

Doe, John, 52


If you wish to add additional properties to the object later, do you need to use the 'this' keyword, and if so, where does it go in the syntax?






javascript constructor







share|improve this question

























  • johnDoe.foo = 'bar';. Also, while comma is not syntactically invalid, it is not good practice to end statements with it. Use a semicolon instead.

    – Patrick Roberts
    Nov 16 '18 at 21:44











  • Whether you need to use this depends on what exactly you mean by "later" and how that code will be called.

    – Bergi
    Nov 16 '18 at 22:16











  • Thanks Robert -- I swapped in semicolons.

    – efw
    Nov 16 '18 at 23:45


















1















When creating an object constructor in Javascript, I understand that it's necessary to prepend property names with the 'this' keyword.



function funcConstruct(first,last,age) {

        this.firstName = first;

        this.lastName = last;

        this.age = age;

        this.fullNameAge = function() {

            return this.lastName + ', ' + this.firstName + ', ' + this.age

        };

};





var johnDoe = new funcConstruct('John', 'Doe', 52);

console.log(johnDoe.fullNameAge()); 

Doe, John, 52


If you wish to add additional properties to the object later, do you need to use the 'this' keyword, and if so, where does it go in the syntax?






javascript constructor







share|improve this question

























  • johnDoe.foo = 'bar';. Also, while comma is not syntactically invalid, it is not good practice to end statements with it. Use a semicolon instead.

    – Patrick Roberts
    Nov 16 '18 at 21:44











  • Whether you need to use this depends on what exactly you mean by "later" and how that code will be called.

    – Bergi
    Nov 16 '18 at 22:16











  • Thanks Robert -- I swapped in semicolons.

    – efw
    Nov 16 '18 at 23:45














1












1








1








When creating an object constructor in Javascript, I understand that it's necessary to prepend property names with the 'this' keyword.



function funcConstruct(first,last,age) {

        this.firstName = first;

        this.lastName = last;

        this.age = age;

        this.fullNameAge = function() {

            return this.lastName + ', ' + this.firstName + ', ' + this.age

        };

};





var johnDoe = new funcConstruct('John', 'Doe', 52);

console.log(johnDoe.fullNameAge()); 

Doe, John, 52


If you wish to add additional properties to the object later, do you need to use the 'this' keyword, and if so, where does it go in the syntax?






javascript constructor







share|improve this question
















When creating an object constructor in Javascript, I understand that it's necessary to prepend property names with the 'this' keyword.



function funcConstruct(first,last,age) {

        this.firstName = first;

        this.lastName = last;

        this.age = age;

        this.fullNameAge = function() {

            return this.lastName + ', ' + this.firstName + ', ' + this.age

        };

};





var johnDoe = new funcConstruct('John', 'Doe', 52);

console.log(johnDoe.fullNameAge()); 

Doe, John, 52


If you wish to add additional properties to the object later, do you need to use the 'this' keyword, and if so, where does it go in the syntax?






javascript constructor




javascript constructor






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 16 '18 at 23:52







efw

















asked Nov 16 '18 at 21:41









efwefw

110110




110110













  • johnDoe.foo = 'bar';. Also, while comma is not syntactically invalid, it is not good practice to end statements with it. Use a semicolon instead.

    – Patrick Roberts
    Nov 16 '18 at 21:44











  • Whether you need to use this depends on what exactly you mean by "later" and how that code will be called.

    – Bergi
    Nov 16 '18 at 22:16











  • Thanks Robert -- I swapped in semicolons.

    – efw
    Nov 16 '18 at 23:45



















  • johnDoe.foo = 'bar';. Also, while comma is not syntactically invalid, it is not good practice to end statements with it. Use a semicolon instead.

    – Patrick Roberts
    Nov 16 '18 at 21:44











  • Whether you need to use this depends on what exactly you mean by "later" and how that code will be called.

    – Bergi
    Nov 16 '18 at 22:16











  • Thanks Robert -- I swapped in semicolons.

    – efw
    Nov 16 '18 at 23:45

















johnDoe.foo = 'bar';. Also, while comma is not syntactically invalid, it is not good practice to end statements with it. Use a semicolon instead.

– Patrick Roberts
Nov 16 '18 at 21:44





johnDoe.foo = 'bar';. Also, while comma is not syntactically invalid, it is not good practice to end statements with it. Use a semicolon instead.

– Patrick Roberts
Nov 16 '18 at 21:44













Whether you need to use this depends on what exactly you mean by "later" and how that code will be called.

– Bergi
Nov 16 '18 at 22:16





Whether you need to use this depends on what exactly you mean by "later" and how that code will be called.

– Bergi
Nov 16 '18 at 22:16













Thanks Robert -- I swapped in semicolons.

– efw
Nov 16 '18 at 23:45





Thanks Robert -- I swapped in semicolons.

– efw
Nov 16 '18 at 23:45












1 Answer
1






active

oldest

votes


















1














You can add additional properties after the fact:



function funcConstruct(first,last,age) {

    this.firstName = first,

    this.lastName = last,

    this.age = age,

    this.fullNameAge = function() {

        return this.lastName + ', ' + this.firstName + ', ' + this.age

    }

};





var johnDoe = new funcConstruct('John', 'Doe', 52);

johnDoe.foo = "bar";


You are using the function constructor pattern, but note that there are other javascript object encapsulation patterns you can use depending on your use case some are better than others. In my opinion, I would use the function constructor pattern only if I was using pre ES6, if using >=ES6 (ES2015) I would use a class, and only if I needed a bunch of instances of the object. Otherwise, I would rather use the revealing module pattern if only a single instance of the object is required. Use fun



No use re-inventing the wheel, the accepted answer and some other highly voted answers to this question give a good summary. This video explains some of the confusion around using this in javascript and provides an opinion that it is probably best to avoid this where possible.






share|improve this answer


























  • Okay that's just uncanny...

    – Patrick Roberts
    Nov 16 '18 at 21:45











  • Should note there are other ways to do it as well such as setter in constructor

    – charlietfl
    Nov 16 '18 at 21:53








  • 1





    Thanks for the answers. I'm new to OOP. I understand there are other patterns for creating objects, and good reasons for avoiding this one, but I just wanted to make sure I understood how it worked on its most basic level.

    – efw
    Nov 16 '18 at 23:42












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1 Answer
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1 Answer
1






active

oldest

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oldest

votes






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oldest

votes









1














You can add additional properties after the fact:



function funcConstruct(first,last,age) {

    this.firstName = first,

    this.lastName = last,

    this.age = age,

    this.fullNameAge = function() {

        return this.lastName + ', ' + this.firstName + ', ' + this.age

    }

};





var johnDoe = new funcConstruct('John', 'Doe', 52);

johnDoe.foo = "bar";


You are using the function constructor pattern, but note that there are other javascript object encapsulation patterns you can use depending on your use case some are better than others. In my opinion, I would use the function constructor pattern only if I was using pre ES6, if using >=ES6 (ES2015) I would use a class, and only if I needed a bunch of instances of the object. Otherwise, I would rather use the revealing module pattern if only a single instance of the object is required. Use fun



No use re-inventing the wheel, the accepted answer and some other highly voted answers to this question give a good summary. This video explains some of the confusion around using this in javascript and provides an opinion that it is probably best to avoid this where possible.






share|improve this answer


























  • Okay that's just uncanny...

    – Patrick Roberts
    Nov 16 '18 at 21:45











  • Should note there are other ways to do it as well such as setter in constructor

    – charlietfl
    Nov 16 '18 at 21:53








  • 1





    Thanks for the answers. I'm new to OOP. I understand there are other patterns for creating objects, and good reasons for avoiding this one, but I just wanted to make sure I understood how it worked on its most basic level.

    – efw
    Nov 16 '18 at 23:42
















1














You can add additional properties after the fact:



function funcConstruct(first,last,age) {

    this.firstName = first,

    this.lastName = last,

    this.age = age,

    this.fullNameAge = function() {

        return this.lastName + ', ' + this.firstName + ', ' + this.age

    }

};





var johnDoe = new funcConstruct('John', 'Doe', 52);

johnDoe.foo = "bar";


You are using the function constructor pattern, but note that there are other javascript object encapsulation patterns you can use depending on your use case some are better than others. In my opinion, I would use the function constructor pattern only if I was using pre ES6, if using >=ES6 (ES2015) I would use a class, and only if I needed a bunch of instances of the object. Otherwise, I would rather use the revealing module pattern if only a single instance of the object is required. Use fun



No use re-inventing the wheel, the accepted answer and some other highly voted answers to this question give a good summary. This video explains some of the confusion around using this in javascript and provides an opinion that it is probably best to avoid this where possible.






share|improve this answer


























  • Okay that's just uncanny...

    – Patrick Roberts
    Nov 16 '18 at 21:45











  • Should note there are other ways to do it as well such as setter in constructor

    – charlietfl
    Nov 16 '18 at 21:53








  • 1





    Thanks for the answers. I'm new to OOP. I understand there are other patterns for creating objects, and good reasons for avoiding this one, but I just wanted to make sure I understood how it worked on its most basic level.

    – efw
    Nov 16 '18 at 23:42














1












1








1







You can add additional properties after the fact:



function funcConstruct(first,last,age) {

    this.firstName = first,

    this.lastName = last,

    this.age = age,

    this.fullNameAge = function() {

        return this.lastName + ', ' + this.firstName + ', ' + this.age

    }

};





var johnDoe = new funcConstruct('John', 'Doe', 52);

johnDoe.foo = "bar";


You are using the function constructor pattern, but note that there are other javascript object encapsulation patterns you can use depending on your use case some are better than others. In my opinion, I would use the function constructor pattern only if I was using pre ES6, if using >=ES6 (ES2015) I would use a class, and only if I needed a bunch of instances of the object. Otherwise, I would rather use the revealing module pattern if only a single instance of the object is required. Use fun



No use re-inventing the wheel, the accepted answer and some other highly voted answers to this question give a good summary. This video explains some of the confusion around using this in javascript and provides an opinion that it is probably best to avoid this where possible.






share|improve this answer















You can add additional properties after the fact:



function funcConstruct(first,last,age) {

    this.firstName = first,

    this.lastName = last,

    this.age = age,

    this.fullNameAge = function() {

        return this.lastName + ', ' + this.firstName + ', ' + this.age

    }

};





var johnDoe = new funcConstruct('John', 'Doe', 52);

johnDoe.foo = "bar";


You are using the function constructor pattern, but note that there are other javascript object encapsulation patterns you can use depending on your use case some are better than others. In my opinion, I would use the function constructor pattern only if I was using pre ES6, if using >=ES6 (ES2015) I would use a class, and only if I needed a bunch of instances of the object. Otherwise, I would rather use the revealing module pattern if only a single instance of the object is required. Use fun



No use re-inventing the wheel, the accepted answer and some other highly voted answers to this question give a good summary. This video explains some of the confusion around using this in javascript and provides an opinion that it is probably best to avoid this where possible.







share|improve this answer














share|improve this answer



share|improve this answer








edited Nov 16 '18 at 22:08

























answered Nov 16 '18 at 21:44









joshweirjoshweir

1,95621137




1,95621137













  • Okay that's just uncanny...

    – Patrick Roberts
    Nov 16 '18 at 21:45











  • Should note there are other ways to do it as well such as setter in constructor

    – charlietfl
    Nov 16 '18 at 21:53








  • 1





    Thanks for the answers. I'm new to OOP. I understand there are other patterns for creating objects, and good reasons for avoiding this one, but I just wanted to make sure I understood how it worked on its most basic level.

    – efw
    Nov 16 '18 at 23:42



















  • Okay that's just uncanny...

    – Patrick Roberts
    Nov 16 '18 at 21:45











  • Should note there are other ways to do it as well such as setter in constructor

    – charlietfl
    Nov 16 '18 at 21:53








  • 1





    Thanks for the answers. I'm new to OOP. I understand there are other patterns for creating objects, and good reasons for avoiding this one, but I just wanted to make sure I understood how it worked on its most basic level.

    – efw
    Nov 16 '18 at 23:42

















Okay that's just uncanny...

– Patrick Roberts
Nov 16 '18 at 21:45





Okay that's just uncanny...

– Patrick Roberts
Nov 16 '18 at 21:45













Should note there are other ways to do it as well such as setter in constructor

– charlietfl
Nov 16 '18 at 21:53







Should note there are other ways to do it as well such as setter in constructor

– charlietfl
Nov 16 '18 at 21:53






1




1





Thanks for the answers. I'm new to OOP. I understand there are other patterns for creating objects, and good reasons for avoiding this one, but I just wanted to make sure I understood how it worked on its most basic level.

– efw
Nov 16 '18 at 23:42





Thanks for the answers. I'm new to OOP. I understand there are other patterns for creating objects, and good reasons for avoiding this one, but I just wanted to make sure I understood how it worked on its most basic level.

– efw
Nov 16 '18 at 23:42




















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