If a function does not return a value, by default, it returns

Return values are just what they sound like — the values that a function returns when it completes. You've already met return values several times, although you may not have thought about them explicitly.

Let's return to a familiar example [from a in this series]:

const myText = "The weather is cold";
const newString = myText.replace["cold", "warm"];
console.log[newString]; // Should print "The weather is warm"
// the replace[] string function takes a string,
// replaces one substring with another, and returns
// a new string with the replacement made

The replace[] function is invoked on the myText string, and is passed two parameters:

1. the substring to find ['cold'].
2. the string to replace it with ['warm'].

When the function completes [finishes running], it returns a value, which is a new string with the replacement made. In the code above, the result of this return value is saved in the variable

function draw[] {
  ctx.clearRect[0, 0, WIDTH, HEIGHT];
  for [let i = 0; i  {
  const num = parseFloat[input.value];
  if [isNaN[num]] {
    para.textContent = "You need to enter a number!";
  } else {
    para.textContent = `${num} squared is ${squared[num]}. `;
    para.textContent += `${num} cubed is ${cubed[num]}. `;
    para.textContent += `${num} factorial is ${factorial[num]}. `;
  }
}];

function random[number] {
  const result = Math.floor[Math.random[] * number];
  return result;
}

function random[number] {
  const result = Math.floor[Math.random[] * number];
  return result;
}

function random[number] {
  const result = Math.floor[Math.random[] * number];
  return result;
}

function random[number] {
  const result = Math.floor[Math.random[] * number];
  return result;
}

function random[number] {
  const result = Math.floor[Math.random[] * number];
  return result;
}

function random[number] {
  const result = Math.floor[Math.random[] * number];
  return result;
}

function random[number] {
  const result = Math.floor[Math.random[] * number];
  return result;
}

function random[number] {
  const result = Math.floor[Math.random[] * number];
  return result;
}

function random[number] {
  const result = Math.floor[Math.random[] * number];
  return result;
}

function random[number] {
  const result = Math.floor[Math.random[] * number];
  return result;
}

ctx.arc[random[WIDTH], random[HEIGHT], random[50], 0, 2 * Math.PI];

ctx.arc[random[WIDTH], random[HEIGHT], random[50], 0, 2 * Math.PI];

function random[number] {
  const result = Math.floor[Math.random[] * number];
  return result;
}

function random[number] {
  return Math.floor[Math.random[] * number];
}

function random[number] {
  return Math.floor[Math.random[] * number];
}

function random[number] {
  const result = Math.floor[Math.random[] * number];
  return result;
}

Note: If you have trouble getting the example to work, feel free to check your code against the finished version on GitHub [see it running live also], or ask us for help.

At this point, we'd like you to have a go at writing out a couple of functions of your own and adding them to the library. How about the square or cube root of the number? Or the circumference of a circle with a given radius?

Some extra function-related tips:

• Look at another example of writing error handling into functions. It is generally a good idea to check that any necessary parameters are validated, and that any optional parameters have some kind of default value provided. This way, your program will be less likely to throw errors.
• Think about the idea of creating a function library. As you go further into your programming career, you'll start doing the same kinds of things over and over again. It is a good idea to create your own library of utility functions to do these sorts of things. You can copy them over to new code, or even just apply them to HTML pages wherever you need them.

You've reached the end of this article, but can you remember the most important information? You can find some further tests to verify that you've retained this information before you move on — see Test your skills: Functions.

So there we have it — functions are fun, very useful, and although there's a lot to talk about in regards to their syntax and functionality, they are fairly understandable.

If there is anything you didn't understand, feel free to read through the article again, or to ask for help.

What will be the default return value if a function does not return anything?

What function does not return a value?

When a function does not return any value what is the by default return value for that function in Python?

What happens if a function does not return anything?