Is it possible to have an object nested within a function? How about a function within a function? I'm determined to grasp

Question

Is it possible to have an object nested within a function? How about a function within a function? I'm determined to grasp

0

Can someone explain to me how the function express() works? I'm having trouble understanding how you can call a function when stored in a variable like const app = express();

Then calling a function like listen() as if it were an object:

app.listen()

Any help in clarifying this would be greatly appreciated.

Thank you in advance!

javascript express nodes

Answer 1

Answer №1

Methods can be assigned to objects, essentially acting as functions within the object structure. The return value of these methods may or may not be significant depending on the context in which they are used.

const myObject = {
  sum: (num1, num2) => num1 + num2;
  display: (message) => console.log(message);
}

const output = myObject.sum(3, 4);
myObject.display(output);

Answer 2

Methods can be assigned to objects, essentially acting as functions within the object structure. The return value of these methods may or may not be significant depending on the context in which they are used.

const myObject = {
  sum: (num1, num2) => num1 + num2;
  display: (message) => console.log(message);
}

const output = myObject.sum(3, 4);
myObject.display(output);

Answer 3

Answer №2

In the world of Javascript, functions are not just simple entities but rather objects with various capabilities. They can be assigned to variables, executed by calling them, and even have properties assigned to them or read from them.

For instance, let's take a look at this example where we assign the module.exports from the 'express' module to a variable named 'express':

const express = require('express');

Now, here's how you would execute the function by calling it:

const app = express();

And finally, accessing the .static property on the express function would look like this:

app.use(express.static('/public'));

Another interesting aspect is that all regular functions come with some built-in properties. For example, considering a function greet(greeting) which prints out the greeting:

function greet(greeting) {
    console.log(greeting);
}

// This will output 1 as the function has one declared argument
console.log(greet.length);

Furthermore, you also have the flexibility to add your own custom properties to functions, thanks to their nature as a sub-class of an object.

Answer 4

In the world of Javascript, functions are not just simple entities but rather objects with various capabilities. They can be assigned to variables, executed by calling them, and even have properties assigned to them or read from them.

For instance, let's take a look at this example where we assign the module.exports from the 'express' module to a variable named 'express':

const express = require('express');

Now, here's how you would execute the function by calling it:

const app = express();

And finally, accessing the .static property on the express function would look like this:

app.use(express.static('/public'));

Another interesting aspect is that all regular functions come with some built-in properties. For example, considering a function greet(greeting) which prints out the greeting:

function greet(greeting) {
    console.log(greeting);
}

// This will output 1 as the function has one declared argument
console.log(greet.length);

Furthermore, you also have the flexibility to add your own custom properties to functions, thanks to their nature as a sub-class of an object.

Answer 5

Answer №3

When a function is nested within another, it cannot be directly accessed from outside the outer function.

However, if a global reference is created for the inner function, it can become accessible.

In this particular scenario, the outerFunction includes two innerFunctions along with variable declarations that assign these functions to their respective variables (outerFunction.innerFunction1 and outerFunction.innerFunction2). Had these been declared using let or const inside the outer function, they would have remained limited to internal access only. But by declaring them without a specific scope, they gain global accessibility.

Therefore, upon invoking the outerFunction, the inner functions are elevated to the global scope and can now be referenced by their assigned names - outerFunction.innerFunction1 and outerFunction.innerFunction2. While naming them with a dot serves as a reminder of their origin, any other name could be used for direct calling (as demonstrated in the third example within the snippet).

function outerFunction(){
    
    function innerFunction1(){
      console.log( 'hello from first innerFunction' );
    } // end innerFunction2;
    
    function innerFunction2(){
      console.log('hello from second innerFunction');
    } // end innerFunction2;

    function innerFunction3(){
      console.log('hello from the third function');
    } // end innerFunction3;
    
  outerFunction.innerFunction1 = innerFunction1;
  outerFunction.innerFunction2 = innerFunction2;
  anyName = innerFunction3;
  
} // end outer function;

outerFunction(); // essential to declare and initialise global variables about to be accessed;
outerFunction.innerFunction1();
outerFunction.innerFunction2();
anyName();

Before diving into the outer function provided in your example, take note of the dot notation variable declaration used for calling. There's nothing mystical about the dot notation; it simply represents a variable name.

Answer 6

When a function is nested within another, it cannot be directly accessed from outside the outer function.

However, if a global reference is created for the inner function, it can become accessible.

In this particular scenario, the outerFunction includes two innerFunctions along with variable declarations that assign these functions to their respective variables (outerFunction.innerFunction1 and outerFunction.innerFunction2). Had these been declared using let or const inside the outer function, they would have remained limited to internal access only. But by declaring them without a specific scope, they gain global accessibility.

Therefore, upon invoking the outerFunction, the inner functions are elevated to the global scope and can now be referenced by their assigned names - outerFunction.innerFunction1 and outerFunction.innerFunction2. While naming them with a dot serves as a reminder of their origin, any other name could be used for direct calling (as demonstrated in the third example within the snippet).

function outerFunction(){
    
    function innerFunction1(){
      console.log( 'hello from first innerFunction' );
    } // end innerFunction2;
    
    function innerFunction2(){
      console.log('hello from second innerFunction');
    } // end innerFunction2;

    function innerFunction3(){
      console.log('hello from the third function');
    } // end innerFunction3;
    
  outerFunction.innerFunction1 = innerFunction1;
  outerFunction.innerFunction2 = innerFunction2;
  anyName = innerFunction3;
  
} // end outer function;

outerFunction(); // essential to declare and initialise global variables about to be accessed;
outerFunction.innerFunction1();
outerFunction.innerFunction2();
anyName();

Before diving into the outer function provided in your example, take note of the dot notation variable declaration used for calling. There's nothing mystical about the dot notation; it simply represents a variable name.

Is it possible to have an object nested within a function? How about a function within a function? I'm determined to grasp

Answer №1

Answer №2

Answer №3

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