JavaScript Functions
Jan 25 2024
What are JavaScript Functions?
- Reusable blocks of code that perform specific tasks.
- Encapsulate logic, making code modular and organized.
- Can accept input (parameters) and produce output (return values).
- Essential for building interactive and dynamic web applications.
A Basic Javascript Function Syntax
function functionName(parameters) {
// Statements to be executed
return value; // Optional
}
-
function
: Keyword indicating function definition. -
functionName
: Name you assign to the function (alphanumeric, underscores, $). -
parameters
: Comma-separated list of values the function expects (optional). -
{}
: Curly braces enclosing the function's body. -
return value
: Value the function returns when executed (optional).
Function Call
Once a function is defined, you can call it by using its name followed by parentheses, optionally passing arguments if the function has parameters.
// Function declaration
function addNumbers(a, b) {
var sum = a + b;
return sum;
}
// Function call
var result = addNumbers(5, 10);
console.log(result); // Output: 15
Anonymous Functions (Function Expressions):
You can also create functions without naming them, known as anonymous functions or function expressions.
var multiply = function(x, y) {
return x * y;
};
var product = multiply(3, 4);
console.log(product); // Output: 12
Arrow Functions (ES6+):
Arrow functions provide a concise syntax for writing functions, especially useful for short and simple functions.
const square = (num) => num * num;
console.log(square(5)); // Output: 25
Callback Functions:
Functions can be passed as arguments to other functions, which is useful for implementing callback functionality.
function doSomething(callback) {
console.log("Doing something...");
callback();
}
function onComplete() {
console.log("Operation complete!");
}
doSomething(onComplete);
Conclusion
These are the fundamental concepts of JavaScript functions. As you get more comfortable with these basics, you can explore more advanced topics like closures, recursion, and higher-order functions