Coding Challenge Practice - Question 110

The task is to implement String.prototype.trim().

The boilerplate code

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

Initialise pointers to move inwards till they hit a whitespace

let start = 0;
let end = str.length - 1;

Trim leading whitespace

while (start <= end && /\s/.test(str[start])) {
  start++;
}

\s matches all types of whitespace characters - spaces, tabs, newlines.

Trim ending whitespace

while (end >= start && /\s/.test(str[end])) {
  end--;
}

Extract the trimmed string

return str.slice(start, end + 1);

The final code

function trim(str) {
  // your code here
  let start = 0;
  let end = str.length - 1;

  while(start <= end && /\s/.test(str[start])) {
    start++;
  }

  while(end >= start && /\s/.test(str[end])) {
    end--;
  }
  return str.slice(start, end + 1) 
}

That's all folks!