12-functions-custom.md

Functions - Custom

• Functions are created/ defined then they are called.

• Defining a function:

    // Function definition
    
    function calculateBill() {
    	// this is the function body
    	console.log('running calculateBill');
    }

• Calling a function:

    // Function call or run
    
    calculateBill(); // running calculateBill (returns undefined)

• Variables created inside a function are not available outside the function. e.g. total above.

  It is a temporary variable. After running of the function is complete, the variable is cleaned up or garbage-collected.

• Returning value from function:

    function calculateBill() {
    	const total = 100 * 1.13;
    	return total; // total is returned
    }
    
    calculateBill(); // returns 112.999999999

• Capturing returned value from a function into a variable:

  const myTotal = calculateBill(); (myTotal will have value 112.999999999)