JavaScript Functions

• Reusable Blocks of Code: Functions are reusable blocks of code that perform a specific task.

• Defining a Function:

  JavaScript

   

  function myFunction(parameter1, parameter2) {
    // Code to be executed
    return result; 
  }
  

• Parameters and Arguments:

  • Parameters: Placeholders for values that are passed into the function when it’s called.
  • Arguments: The actual values that are passed to the function when it’s invoked.

• Calling a Function:

  JavaScript

   

  const result = myFunction(argument1, argument2); 
  

• Return Statement:

  • The return statement specifies the value that the function should output.
  • If no return statement is used, the function will return undefined.

• Function Types:

  • Named Functions: Defined using the function keyword (as shown above).
  • Anonymous Functions: Functions without a name, often used as callback functions.
  • Arrow Functions: A concise syntax for writing functions: const myArrowFunction = (param1, param2) => { ... }

• Examples:

  • Simple Function:

    JavaScript

     

    function greet(name) {
      return "Hello, " + name + "!";
    }
    const greeting = greet("John"); 
    

  • Function with Multiple Parameters:

    JavaScript

     

    function add(a, b) {
      return a + b;
    }
    const sum = add(5, 3); 
    

• Importance:

  • Reusability: Avoid code duplication by defining functions for commonly used tasks.
  • Modularity: Break down complex problems into smaller, more manageable functions.
  • Readability: Improve code readability and maintainability by using meaningful function names.

Functions are essential building blocks in JavaScript, enabling you to write organized, efficient, and reusable code.