JavaScript functions are fundamental building blocks in the language, encapsulating reusable code. Let’s explore how functions are defined and their distinctive characteristics in comparison to similar constructs in languages like Java and C++.
Here’s a simple function in JavaScript that adds two numbers:
function total(x, y) {
return x + y;
}Functions in JavaScript share several core features with functions in other programming languages:
return statement, which also terminates the function execution immediately.Unlike in Java or C++, JavaScript functions are less rigid:
undefined.A unique aspect of JavaScript functions is their first-class status; they are treated as values. This allows functions to be assigned to variables, passed as arguments to other functions, or even returned from functions.
const sum = total; // Assigning function to a variable
console.log(sum(2, 1)); // Calling the function via its new referenceTerminology: A higher-order function is one that either takes a function as an argument or returns a function. In contrast, a first-order function does neither.
JavaScript supports both first and higher-order functions, enhancing its flexibility and expressive power.
To execute a function in JavaScript, you use its name followed by parentheses, optionally including arguments:
const result = total(2, 1)When referencing a function without intending to call it, simply use the function name without parentheses. This can be useful for passing the function as a value or assigning it to another variable:
const sum = total; // Referencing the function
const result = sum(2, 1); // Calling the function via its alias