Functions review

Lets review functions!

function biggerOf(num1, num2) {
  if (num1 > num2) {
    return num1
  } else {
    return num2
  }
}

console.log(biggerOf(3, 20))
console.log(biggerOf(300, 20))
const biggerNum = biggerOf(23 * 4, 13 * 14))
console.log(biggerNum)

What happens if....

  • I don't have a return at all in the function?

  • I try to console.log(num1) outside the function? After the function? After the function is called?

  • What if I use const or let to create a variable inside the function?

  • How many parameters can I have?

  • What happens if I put some code after the return?

How do I return multiple bits of information from a function? Build this function:

function longestAndShortestWord(words) {}

The transform it into this function, returning an object: 

{ longest: 'sentence', shortest: 'a' }
function longestAndShortestWord(words) {
  let longestSoFar = "";
  for (let word of words) {
    if (word.length > longestSoFar.length) {
      longestSoFar = word;
    }
  }
  return longestSoFar;
}

longestAndShortestWord(["this", "is", "a", "sentence", "yeah"]);

Arrow functions

An arrow function expression is a compact alternative to a traditional function expression, with some semantic differences and deliberate limitations in usage:

Syntax

param => expression

(param) => expression

(param1, paramN) => expression

param => {
  statements
}

(param1, paramN) => {
  statements
}

Now lets rewrite the above function as an arrow function

const longestAndShortestWord = (words) => {
  let longestSoFar = "";
  for (let word of words) {
    if (word.length > longestSoFar.length) {
      longestSoFar = word;
    }
  }
  return longestSoFar;
};

One more example, let write a function to multiply two numbers

// Notice the lack of return when there are no wrapping curly brackets
const multiply = (num1, num2) => num1 * num2

Try rewriting functions you've using the arrow function syntax =>

References

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