Coding Challenge Practice - Question 109

The task is to implement a function that converts snake case to camel case.

The boilerplate code

function snakeToCamel(str) {
  // your code here
}

To convert from snake_case to camelCase, it is required that the connecting underscore be removed and the next word has its first letter capitalised. Leading underscores, trailing underscores and double underscores should be kept.

Initialize variables to build the final string and a pointer to walk through the string

let result = '';
let i = 0;

Loop through the string manually

while (i < str.length)

Determine the conditions that ensure only underscores that connect words are removed

if (
  str[i] === '_' &&
  i > 0 &&
  i < str.length - 1 &&
  /[a-zA-Z]/.test(str[i + 1]) &&
  str[i - 1] !== '_'
)

Convert the next character correctly. If it is lowercase, convert to uppercase. If it is uppercase, leave it

const nextChar = str[i + 1];

result += nextChar >= 'a' && nextChar <= 'z'
  ? nextChar.toUpperCase()
  : nextChar;

Skip the underscore and the next character

i += 2;

Copy as-is if there is no underscore

else {
  result += str[i];
  i++;
}

Return the final string

return result;

The final code

function snakeToCamel(str) {
  // your code here
 let result = "";
 let i = 0;

 while(i < str.length) {
  if(str[i] === '_' && i > 0 && i < str.length - 1 &&  /[a-zA-Z]/.test(str[i + 1]) && str[i - 1] !== '_') {
   const nextChar = str[i + 1];
   result += nextChar >= 'a' && nextChar <= 'z' ? nextChar.toUpperCase() : nextChar;
   i += 2;
  } else {
    result += str[i];
    i++;
  }
 }
 return result;
}

That's all folks!