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7.1 - Functions? The math ones?

functions in programming

Functions are a useful tool where we can store code separately so we don’t have to rewrite it. This reduces repetitiveness in code, because you can just call functions multiple times!

To define a function in JavaScript:

  1. Use the function keyword
  2. Give it a name
  3. List parameters, or inputs, inside parentheses ((…))
  4. Write the body between { … }
  5. Use return to specify the output
function addNums(a, b) {
  return a + b;
}

let result1 = addNums(4, 5);
let result2 = addNums(10, 11);

console.log(result1); // 9
console.log(result2); // 21

In the above function, the name is addNums, parameters are a and b, and the body is return a + b You can call it multiple times with different input to reuse the same logic.

question

What does the return keyword do inside a function? Can you explain the difference between calling a function and defining it?

tasks

  1. Create a function called greet that takes one parameter (name) and returns "Hello, [name]!"
  2. Call your greet function with different names and print the result
  3. Create a function called multiply that takes two numbers and returns their product
  4. Print out the result of calling multiply(3, 4) and multiply(7, 2)

Bonus: Try writing a function that takes a number and returns whether it's even or odd