Need Help to Explain Basic JavaScript - Use Recursion to Create a Range of Numbers

[Habushu]

Tell us what’s happening:
Hello everyone,

your help will be needed to explain this chapter to me. I’ve pass this exercise with a bit help from the hints. However im not quite sure how this can make a “loop” cause it looks like a one time call to me? why do we need - 1 after the endNum? and how is that showing array as a result? is it because we use .push() and thats automatically makes an array?

  **Your code so far**

function rangeOfNumbers(startNum, endNum) {
if (endNum < startNum) {
  return [];
} else {
  const numbers = rangeOfNumbers(startNum, endNum - 1);
  numbers.push(endNum);
  return numbers;
}
}

  **Your browser information:**

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36

Challenge: Basic JavaScript - Use Recursion to Create a Range of Numbers

Link to the challenge:

freeCodeCamp.org

[hbar1st]

Try to run this function instead (with some logs)

function rangeOfNumbers(startNum, endNum) {
console.log(“Enter-“+ startNum + “, “+ endNum +”\n”);
if (endNum < startNum) {
  return [];
} else {
  const numbers = rangeOfNumbers(startNum, endNum - 1);
  numbers.push(endNum);
console.log(“after push: “+numbers.toString() +”\n”);
  return numbers;
}
}

Hopefully this will help you see what is happening.

[isurumaldeniya]

I have created a flow chart with draw.io to explain what is happening. Hope this help you.

[ugwen]

i found this helpfull for myself but i struggled to get your code as is working and wrote simplified:

function rangeOfNumbers(startNum, endNum) {
console.log('startnum/endnum @start:',startNum ,endNum );
if (endNum < startNum) {
  return [];
} else {
  const numbers = rangeOfNumbers(startNum, endNum - 1);
  numbers.push(endNum);
  console.log('after push:',numbers);
  return numbers;
}
}
console.log('result', rangeOfNumbers(1,3))

[hbar1st]

yes sorry, my cellphone uses the wrong type of double-quotes (they needed to be changed to work)

Did you have any further question as you saw the log?

[ugwen]

me? no, it works fine with the fixes, and i only fixed the log lines. the code is fine.
(‘\n’ always seems to be default in fcc editor)