ex23.js

function trim(str = '', whitespaceopt = ' ') {
    let result = ''
  
    // Interval to keep
    let start = 0
    let end = str.length - 1
  
    // Retrieve start index
    for (start; start < str.length; start++) {
      if (str[start] !== whitespaceopt) {
        break
      }
    }
  
    // Retrieve end index
    for (end; end > 0; end--) {
      if (str[end] !== whitespaceopt) {
        break
      }
    }
  
    for (let i = start; i <= end; i++) {
      result += str[i]
    }
  
    return result
  }
  
  console.log(trim(' Tony Tony Ch0pper '))
  // => 'Tony Tony Ch0pper'
  console.log(trim('--Tony Tony Ch0pper--', '-'))
  // => 'Tony Tony Ch0pper'