Add spaces to a particular index within a string

Question

Add spaces to a particular index within a string

I'm currently tackling a challenging problem on Codewars.

Objective

Your goal in this Kata is to develop a function that transforms a string into a Mexican Wave. The output should be an array where each uppercase letter represents a person standing up.

Guidelines

The input string will always be in lowercase, but it may be empty.

If the character in the string is whitespace, treat it as an empty seat. Example wave("hello") => ["Hello", "hEllo", "heLlo", "helLo", "hellO"]

Click here to view my current code on repl.it

This is my thought process:

Convert argument into an array
Modify each index of the array accordingly to create a wave pattern
Transform the array back into a string
Add spaces before logging to the console and then repeat the loop

I am struggling with figuring out how to use

for(var j = 0; j < indexSpaceNumber.length; j++){
      //join and add in the spaces at their former index before returning string
      strToArray[indexSpaceNumber[j]].slice(0, " ");
      }

To correctly insert spaces into the string.

Any guidance or tips would be greatly appreciated. I feel like I am so close, yet also frustratingly far from solving this.

javascript arrays string split slice

Answer 1

Answer №1

The concept revolves around the following steps:

Iterate through each character
Replace the original character in the string with an uppercase equivalent

To achieve this, you can utilize Array.from() to convert the string into an array, and then map each element to a new string. If a character is a space, return something falsy (an empty string as per the example). Once the array is created, filter out all falsy values:

const wave = str =>
  Array.from(str, (c,i) => // convert the string to an array
    // replace the original character with its uppercase version 
    c === ' ' ?
    ''
    :
    `${str.substring(0, i)}${c.toUpperCase()}${str.substring(i + 1)}`
  ).filter(c => c)

const result = wave("hello") 

console.log(result)

Answer 2

The concept revolves around the following steps:

Iterate through each character
Replace the original character in the string with an uppercase equivalent

To achieve this, you can utilize Array.from() to convert the string into an array, and then map each element to a new string. If a character is a space, return something falsy (an empty string as per the example). Once the array is created, filter out all falsy values:

const wave = str =>
  Array.from(str, (c,i) => // convert the string to an array
    // replace the original character with its uppercase version 
    c === ' ' ?
    ''
    :
    `${str.substring(0, i)}${c.toUpperCase()}${str.substring(i + 1)}`
  ).filter(c => c)

const result = wave("hello") 

console.log(result)

Answer 3

Answer №2

To transform strings with spaces

function capitalizeWithWave(str) {
  let result = []
  str.toLowerCase().split('').forEach((value, index) => {
    if(value == ' ') return;
    result.push( str.substr(0, index) + value.toUpperCase() + str.substr(index + 1) )
  });
  return result
}

console.log(capitalizeWithWave("hello hello"))

Answer 4

To transform strings with spaces

function capitalizeWithWave(str) {
  let result = []
  str.toLowerCase().split('').forEach((value, index) => {
    if(value == ' ') return;
    result.push( str.substr(0, index) + value.toUpperCase() + str.substr(index + 1) )
  });
  return result
}

console.log(capitalizeWithWave("hello hello"))

Answer 5

Answer №3

I'd choose recursion ;)

Consider that a string of length n requires an array of the same length as your exit condition.

You can determine the pattern for the next string based on the length of the array in each iteration:

hello []            [Hello]              0: uppercase 1st char and append
hello [Hello]       [Hello hEllo]        1: uppercase 2nd char and append
hello [Hello hEllo] [Hello hEllo heLlo]  2: uppercase 3rd char and append
...

const wave =
  (str, arr = []) =>
    str.length === arr.length
      ? arr
      : wave
          ( str
          , [ ...arr
            ,   str.slice(0, arr.length)
              + str[arr.length].toUpperCase()
              + str.slice(arr.length + 1)
            ]
          );

console.log(wave('hello'));

Answer 6

I'd choose recursion ;)

Consider that a string of length n requires an array of the same length as your exit condition.

You can determine the pattern for the next string based on the length of the array in each iteration:

hello []            [Hello]              0: uppercase 1st char and append
hello [Hello]       [Hello hEllo]        1: uppercase 2nd char and append
hello [Hello hEllo] [Hello hEllo heLlo]  2: uppercase 3rd char and append
...

const wave =
  (str, arr = []) =>
    str.length === arr.length
      ? arr
      : wave
          ( str
          , [ ...arr
            ,   str.slice(0, arr.length)
              + str[arr.length].toUpperCase()
              + str.slice(arr.length + 1)
            ]
          );

console.log(wave('hello'));

Answer 7

Answer №4

Iterate through each character in a string and create a new string by:

const wave = str => {
  const res = [];
  for (let i = 0; i < str.length; i++) {
    res.push(`${str.slice(0, i)}${str[i].toUpperCase()}${str.slice(i + 1)}}`);
  }
  return res;
};

console.log(wave("hi my name is rylan"));

// Another approach using Array.splice
const wave2 = str => {
  const res = [];
  for (let i in str) {
    const temp = Array.from(str);
    temp.splice(i, 1, temp[i].toUpperCase());
    res.push(temp)
  } 
  return res.map(x => x.join(''));
};

console.log(wave2("hi my name is rylan"));

Answer 8

Iterate through each character in a string and create a new string by:

const wave = str => {
  const res = [];
  for (let i = 0; i < str.length; i++) {
    res.push(`${str.slice(0, i)}${str[i].toUpperCase()}${str.slice(i + 1)}}`);
  }
  return res;
};

console.log(wave("hi my name is rylan"));

// Another approach using Array.splice
const wave2 = str => {
  const res = [];
  for (let i in str) {
    const temp = Array.from(str);
    temp.splice(i, 1, temp[i].toUpperCase());
    res.push(temp)
  } 
  return res.map(x => x.join(''));
};

console.log(wave2("hi my name is rylan"));

Add spaces to a particular index within a string

Answer №1

Answer №2

Answer №3

Answer №4

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