Basic JavaScript: Use Recursion to Create a Range of Numbers (I do not understand how it works)

Tell us what’s happening:
I do not understand how it works. When I call the rangeOfNumbers function than how it comes that the numbers.push and return works. Can someone please explain it to me.

Your code so far


function rangeOfNumbers(startNum, endNum) {
 if (startNum - endNum == 0) {
  return [startNum];
} else if (startNum <= endNum) {
  var numbers = rangeOfNumbers(startNum, endNum - 1);    
  return numbers;

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Challenge: Use Recursion to Create a Range of Numbers

Link to the challenge:


what do you mean how push and return works?
push is an array method, it add its argument(s) to the end of the array it is used on.
return is used to set what’s the output of the function

recursion means that the function call itself

inside the function, there is the call rangeOfNumbers(startNum, endNum -1)

the function is called over and over till the condition that stops the recursion is met

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This is the point when the function runs itself right:
var numbers = rangeOfNumbers(startNum, endNum - 1);
So, when the code above runs itself how the codes below start to run?

  return numbers;

I mean it is kind of loop right how it reaches the code below? (the push and return code)

the function keeps calling itself till it reaches this, then the last function call has an output, which is then used to the second last to give a value to the numbers variable, then the array has the push method called on, and is then outputted by the function, the third to last call uses this array to give a value to his numbers variable and so on

function rangeOfNumbers(startNum, endNum) {

  if(startNum > endNum)


    return [];


  else {

    const rangeArray = rangeOfNumbers(startNum,endNum-1);


    return rangeArray;



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