Recursively add to strings in JS

Question

I'm tackling a recursion problem that returns a string of "hi"'s where the first "hi" has a capital H and the string ends with an exclamation point. I have the code below so far but I'm not sure how to prevent subsequent occurrences of "hi" having a capital H. Any guidance would be welcome.

function greeting(n) {
  if (n === 0) {
    return "";
  } else if (n === 1) {
    return "Hi!"
  } else {
    return `${'Hi' + greeting(n - 1)}`
  }
}
console.log(greeting(3)) // should return Hihihi!
console.log(greeting(5)) // should return Hihihihihi!

I need it to return Hihihi! My current code capitalises all the H's — ruggle
– ruggle, Commented Jan 23, 2021 at 5:46
Just a .toLowerCase() is missing in your code. ${'Hi' + greeting(n - 1).toLowerCase()}. You don't need the n === 1 step. — Praveen Kumar Purushothaman
– Praveen Kumar Purushothaman, Commented Jan 23, 2021 at 13:57

Nick · Accepted Answer · 2021-01-23 05:45:36Z

1

One way to work around your problem is to pass a flag to the function which indicates whether this is the first call, and only in that case capitalise the hi. Note that you can simplify the code slightly by returning a ! when n == 0; then you don't need to special case n == 1:

function greeting (n, first = true) {
  if (n === 0) {
    return "!";
  } 
  else {
    return `${(first ? 'Hi' : 'hi') + greeting(n - 1, false)}`
  } 
}
console.log(greeting(3)) // should return Hihihi!
console.log(greeting(5)) // should return Hihihihihi!

answered Jan 23, 2021 at 5:45

Nick

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Comments

Praveen Kumar Purushothaman · Accepted Answer · 2021-01-23 13:58:46Z

0

Just a .toLowerCase() is missing in your code.

`${'Hi' + greeting(n - 1).toLowerCase()}`

You don't need the n === 1 step.

function greeting(n) {
  if (n === 0) {
    return "!";
  } else {
    return `${'Hi' + greeting(n - 1).toLowerCase()}`
    //------------------------------^^^^^^^^^^^^^^
  }
}
console.log(greeting(3)) // should return Hihihi!
console.log(greeting(5)) // should return Hihihihihi!

answered Jan 23, 2021 at 13:58

Praveen Kumar Purushothaman

167k27 gold badges215 silver badges261 bronze badges

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