In the Computer Science Course, you will find different unique concepts that are related to certain Programming Languages. And those concepts would only be possible with that Coding Concept. The “JavaScript Nested Functions” is one of the similar topics.
In the Nested Function of JavaScript, you are going to witness some of the important concepts that you might not have come across yet in your life. You are going to be fascinated when we unfold some of the deeper concepts of the JavaScript Nested Function.
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So, take a deep breath & make yourself ready to witness an extensive journey with the JavaScript Programming Language. So, let us start the discussion.
Summary or Key Highlights:
Nested Function is one of the major properties of JavaScript Language.
Nested Functions are such a function that has two kinds of scopes involved.
In Nested Functions, there will be an Outer Function or Parent Function and an Inner or Child Function.
The Working of Nested Functions is different from the Normal Functions in JavaScript.
There are some instances when the use of Nested Functions is necessary.
What Is The Nested Function In JavaScript?
Before moving to implement JavaScript Nested Functions, it is necessary to understand the complete concept. From the term “Nested Functions” are you getting any similarity with other programming concepts? Where have you heard the term “Nested” in programming earlier?
You have heard about the “Nested” term earlier in Loop Concept & Conditional Statements.
If any element is present inside of each other, then it will be called as the Nested Elements. In Nested Functions, there are two functions defined one inside another. That means the Nested Function Definition can be done with the help of two or more functions.
In this perspective, the concept of the Outer Functions & Inner Functions arrives. Let us discuss the idea in the following part.
What Are Inner Function And Outer Function In Nested Functions?
Now, we have to understand what is known as the Inner and Outer Functions in Nested Functions. From the name itself, you can understand the appearance of the function. The Outer Part is placed at the beginning of the Nested Functions.
That means the Outer Function defined will be first. Then, inside of the Outer Part, the Inner Function will be declared. Inside the Inner Case, there will not be any kind of functions present. So, the Nested Function definition can be done like that.
There can be many Inner Functions present inside of the Outer Part. Now, we are going to check the Nested Function Declarations in the upcoming topic where the Syntax of the Function Definition will be implemented.
What Will Be The Syntax Of Nested Function In JavaScript?
Now whatever we have discussed till now, should give some insights about the Function Nested In JavaScript. However, they are not enough to clarify the entire concept. So, before moving to create Functions in Nested, we have to understand the syntax.
The Nested Function Declaration is very simple. The Containing Function will have the Outer Function & inside of that the Inner Function will be defined. Now, you can enter some of the statements in the Inner Function.
function outerfunction() {
function innerfunction() {
// Statements
}
innerfunction();
}
outerfunction();
At the end of the Function Declarations, the Inner Function & Outer Function should be closed. The Inner Function should be closed first before the Outer Function. We hope the Syntax will be enough to clear the concept of Function Nested In JavaScript more.
How To Implement The Nested Function In JavaScript?
Now, as the Syntax of the Function Nested In JavaScript is cleared, we can move to the Implementation of a JavaScript Program on the same. Here, we will define the program in a very simple format that will help to understand the concept.
Here, the structure of the program might not be the same as the above syntax because here we will use the Outer Function & Inner Function with some argument values. Let us check the following example to understand the process.
function outer(a) { // Outer Function
return function inner(b) { // Inner Nested Function
console.log("The Output: ", a * b); // Printing The Output
};
}
outer(3)(4); // Calling Outer Function
Steps Of The Program:
At first, the Outer Scope Chain, the Outer Function will be declared along with Argument A.
Now inside that, the Inner Return Function will be declared along with Argument B.
Now, inside the child function, we will multiply two arguments with any local variable.
At the end, we will use the callback functions to get the Outer Scope Function.
Output:
From the above output, we can see that the Multiplication Result is coming as the Output. So, the Inner Scope of the Function is working fine with the Outer Scope. That is the reason, the Arguments are evaluated nicely.
How Do The Access Variables Work In The Nested Function Of JavaScript?
The Concept of the Function Nested In JavaScript should be cleared with the above example. Now, we will show how All the Variables work with the Function Nested In JavaScript. We will use Global Variable, Outer Variable & Inner Variable there.
For that purpose, we will implement a small JavaScript Program. We will not perform any calculations in that program. Rather, some simple statements will clarify the concept. Let us concentrate on the following example.
let gvar = "Global"; // Global Scope Variable
function outer() { // Outer Function
let ovar = "Outer"; // Outer Scope Variable
function inner() { // Inner Function
let ivar = "Inner"; // Inner Scope Variable
console.log(gvar, "Accessed"); // Global Is Accessible
console.log(ovar, "Accessed"); // Outer Is Accessible
console.log(ivar, "Accessed"); // Inner Is Accessible
}
inner();
}
outer();
Steps Of The Program:
The Global Variable will be declared outside of every function in the Global Scope.
After the Global Scope, in the Outer Function, another variable is declared.
Inside of the Child Function, the Inner Variable is declared.
Now, from the Child Function, we are trying to access every variable defined inside each scope.
At last, we will call the Inner & Outer Functions to complete the process.
Output:
The above discussion shows that every variable declared in the JavaScript Program can be accessed from the Child Function Scope. So, it is proved that the Global, Outer, and Inner, function is accessible from the Inner Scope of the Nested Functions.
What Can Be An Advanced Example of Nested Function In JavaScript?
Now, before we are going to end the discussion, we want to provide a way out to some potential advanced questions related to the Functions Nested In JavaScript. Here, we are going to implement the Recursive Function implemented with Functions Nested In JavaScript.
You might know what is the Recursive Calls & Recursive Functions in different programming languages. Here, we are going to implement the same but with a different taste. Let us have a look at the following program in JavaScript.
function fact(n) { // Outer Function
function recur(x) { // Inner Function
if (x <= 1) // Base Condition
return 1;
return x * recur(x - 1); // Recursive Calling
}
return recur(n); // Returning Value
}
console.log("The Factorial Data: ", fact(5));
Steps Of The Program:
At first, the Outer Part of the Function Fact() will be implemented that will get the N as an argument.
Inside that, the Child Function, Recur() will be implemented which will take another argument as the X.
Now inside the Child Function, we will implement the Recursion Logic that is used for every programming language.
At the end, we will return the Child Function Value to the program to print the result.
We are going to call the Outer Fact() Function Value 5.
Output:
From the above output, we can see that the Factorial Value 120 is coming which is the correct result. So the Factorial Function is working fine with the Functions Nested In JavaScript approach. So, all the logic developed in the program is successful.
Also, while studying Python the programmer needs to declare the data type before declaring one variable. And, this is done using type conversion.
Are Nested Functions Bad?
Now, before we going to end the discussion, we should shed some light on some specific questions. One of the best questions will be the Is Functions Nested In JavaScript Bad to Use? And there is no specific answer present with it.
The use of Nested Functions depends upon circumstances. And you have to be very cautious not to use the Functions Nested In JavaScript every time without any specific purpose. However, there are some cases where the use of Functions Nested In JavaScript is completely prohibited.
The Functions Nested In JavaScript should not be used in Large Objects along with some Large Loops. When you use the Functions Nested In JavaScript, you should be aware that the Code Reuseability will be very low there.
Also, the use of the Functions Nested In JavaScript should not be done for the programs that are going to pass through a high debugging process. If you keep these points in mind, then you will find the Nested Functions are Good to Use.
When To Use Nested Functions? Read Below
Now, after the above discussion, we have got the knowledge of when not to use the Functions Nested In JavaScript. But what are some circumstances when the need to use the Functions Nested In JavaScript becomes necessary? Here, we are going to discuss those points.
We have to check the following points to understand the circumstance when we can use the Functions Nested In JavaScript. There are many different reasons to use Functions Nested In JavaScript. Let us check them.
Encapsulation: If you want to do the Encapsulation of any certain function, then making them Nested should be the best idea. All the parts of the function will be kept altogether which will help to make it secure. There’s also another concept in programming called abstraction. In case you’re interested to know the difference between Encapsulation and Abstraction, you can check out our article.
Closure: If you want to create the Closure, then the Function Nested should be created. In this case, the Child Function can call the elements of the Outer Functions. Such a practice helps a lot in big projects.
Local Scope: In the Function Nested, all the values & variables declared in those two functions are native to them only. This will make them the Local Variables and hence, the naming conflicts can be reduced further in the program.
Readability: The Function Nested increased the Readability of any JavaScript program. As two or more parts of the program in any function come together, this helps to understand the code as well as the logic in parallel.
Conclusion:
In the end, we can say it is very important to understand the “JavaScript Nested Functions”.
Before jumping for the Function Nested Concept in JavaScript, it is very necessary to grasp all the Basics of JavaScript. If your Basic Concept is cleared, then you can easily move for a complex concept like Function Nested in JS.
Apart from JavaScript, you must be learning HTML and CSS courses. But solving HTML & CSS assignments could be challenging and in this case, you can ask for HTML assignment help.
Takeaways:
The Nested Function is the concept made with Outside Function & Inside Function.
Two or more Inside Functions can be present in the Function Nested in JavaScript.
We can pass Arguments to both of the functions in the Function Nested.
The Child Function works first before the Outside Function in the Function Nested.
All kinds of Variables can be accessed from the Child Function of Nested Function.
The Function Nested can’t be used in all fields whenever it is needed.
