Javascript returning "empty" strings inside an array

Question

I'm trying to create a function that returns a "staircase". The output needs to look like this:

  var staircase5 = [
        "    #",
        "   ##",
        "  ###",
        " ####",
        "#####"
    ]

The code I've written so far is:

function staircase (valueA){
    const array1 = [];
    for (let i = 0; i < valueA; i++){
        let cicle = valueA[i];
        let step = " #".repeat(cicle);
        array1.push(step)
    }
console.log(array1);
}

When I run the code in VS Code, console.log(staircase(3)); , this is the result:

[ '', '', '' ]
undefined

Any clue as to why it is returning the strings as ' ' instead of '#'? And why is it not really repeating? Thanks a lot!

If you are passing 3, then valueA is 3, which is not an array or array-like object, so passing an index to it valueA[i] returns undefined. If you open your developer tools and look at the console, you'll see an error about it. — Scott Marcus
– Scott Marcus, Commented Jul 13, 2020 at 18:56
As I said, you can't pass an index to a number. Just i will give you the number of the current loop iteration, not valueA[i]. — Scott Marcus
– Scott Marcus, Commented Jul 13, 2020 at 19:00
@DominikMatis: Not really, hev1's answer works better for me. Thanks a lot anyways. — lwisi
– lwisi, Commented Jul 13, 2020 at 19:04

Unmitigated · Accepted Answer · 2020-07-13 18:58:19Z

1

You are currently trying to treat valueA, which is a number, like an array. If you loop from 1 to valueA, then each step should be the space repeated value - i times concatenated with the # character repeated i times.

function staircase (valueA){
    const array1 = [];
    for (let i = 1; i <= valueA; i++){
        let step = " ".repeat(valueA - i) + "#".repeat(i);
        array1.push(step)
    }
    return array1;
}
console.log(staircase(5))

answered Jul 13, 2020 at 18:58

Unmitigated

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2 Comments

lwisi Over a year ago

This is working for me! Thanks a lot. As soon as I can accept the answer I will.

Unmitigated Over a year ago

@LuisArgüelles No problem.

Dominik Matis · Accepted Answer · 2020-07-13 18:57:37Z

0

You need to use padding.

const staircase = count => {
    let array1 = [];
    let step = ""
    for (let i = 0; i < count; i++){
        step = "#".repeat(i+1);
        array1 = [...array1, step.padStart(count, ' ')]
    }
    console.log(array1);
}

staircase(5)

answered Jul 13, 2020 at 18:57

Dominik Matis

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2 Comments

Scott Marcus Over a year ago

Read the comments under the question. The OP is trying to pull an index of a number. You've provided a working answer without answering the question as to what is wrong.

Dominik Matis Over a year ago

"I've updated the question to show how I'm calling the function: console.log(staircase(3)); – Luis Argüelles 3 mins ago" ... really?

Martin Gainza · Accepted Answer · 2020-07-13 19:22:07Z

If you need your output look like this:

  var staircase5 = [
        "    #",
        "   ##",
        "  ###",
        " ####",
        "#####"
    ]

Your function should be like this:

function staircase (valueA){
    const array1 = [];
    for (let i = 1; i <= valueA; i++){
        let step = " ".repeat(valueA-i)+"#".repeat(i);
        array1.push(step)
    }
  return array1
}

Explanation

In your function:

 function staircase (valueA){
     const array1 = [];
     for (let i = 0; i < valueA; i++){
         let cicle = valueA[i];
         let step = " #".repeat(cicle);
         array1.push(step)
     }
     console.log(array1); 
  }

I supposse you are calling the function like this:

var staircase5 = staircase(5);

In this line: let cicle = valueA[i]; you are trying to take each value of valueA (as an array) and in this line: for (let i = 0; i < valueA; i++) you are using it as a number.

and in this line: let step = " #".repeat(cicle); if your valuaA is equal to 5 your output will be:

[
   " # # # # #",
   " # # # # #",
   " # # # # #",
   " # # # # #",
   " # # # # #"
]

In my solution I use i in " ".repeat(valueA-i)+"#".repeat(i); to iterate between the values that you need to make the array.

When i increment " ".repeat(valueA-i) will render less spaces. (ie: if i=2 and valueA=5, step will be: " ", 3 spaces)

Test:

function staircase (valueA){
    const array1 = [];
    for (let i = 1; i <= valueA; i++){
        let step = " ".repeat(valueA-i)+"#".repeat(i);
        array1.push(step)
    }
  return array1
}

var staircase5 = staircase(5);

console.log(staircase5)

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