Functions Notebook
JavaScript Functions
Functions are the building blocks of readable, maintainable, and reusable code. In JavaScript, functions are first-class citizens, meaning they can be assigned to variables, passed as arguments, and returned from other functions.
1. Function Declaration
The standard way to define a function.
IN [ ]
function greet(name) {
return "Hello, " + name + "!";
}
console.log(greet("Alice"));2. Function Expression
Assigning a function to a variable. These are not hoisted like declarations.
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const square = function(number) {
return number * number;
};
console.log(square(4));3. Arrow Functions (ES6)
A concise syntax for writing function expressions. They do not have their own this context.
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const multiply = (x, y) => x * y;
console.log(multiply(5, 10));
// Single line arrow functions have implicit return
const double = x => x * 2;4. Default Parameters
Setting default values for arguments.
IN [ ]
function welcome(user = "Guest") {
console.log(`Welcome, ${user}`);
}
welcome();
welcome("Rahul");