Functions as first-class citizens:

JavaScript considers functions first-class citizens, allowing them to work equally to other data types, including strings, objects, arrays, etc.

The following operations can be performed when functions are considered as first-class citizens:

• They are assigned to a variable.
• Incorporate them as object characteristics.
• Use arrays to store them.
• Use them as function arguments or function returns.

Higher-order functions are only conceivable since functions in functional programming are treated as first-class citizens.

Now that we've discussed the fundamental principle of JavaScript that allows us to develop higher-order functions, let's dive into higher-order functions in JavaScript.

Higher-order functions:

Higher-order functions accept functions as input and return a function as an output. Examples of Higher-Order functions include a map, filter, and reduce, all of which may be used with the Array.prototype.

Let's examine several instances of each circumstance to better comprehend it.