Функция, преобразующая строку, чередуя верхний и нижний регистр букв

function toWeirdCase(string){
    string = string.toLowerCase();
    let myStr = [];
    let arr = string.split(' ');
    for (let word of arr) {
        for (let i = 0; i <= word.length-1; i+=2) {             
                word = word.replace(word[i], word[i].toUpperCase());                 
            }
        myStr.push(word);
    }
    return myStr.join(' ');
}
 
console.log(toWeirdCase('LOokS LiKe YoU PaSsEd'))//  'LoOkS LiKe YoU PaSsEd'
console.log(toWeirdCase('This is a test'))// 'ThIs Is A TeSt'

function toWeirdCase(string) {
    let str = string.toLowerCase().split('');
    let j = 0;
    for ( let i = 0; i < str.length; i++ ) {
        if ( str[i] == ' ' ) {
            j = 0;
            continue;
        } else {
            if ( j % 2 == 0 ) {
                str[i] = str[i].toUpperCase();
            }
            j++;
        }
    }
    return str.join('');
}

function toWeirdCase(str) {
  return str.replace(/\S+/g, (word) =>
    word.replace(/./g, (letter, i) =>
      letter[["toUpperCase", "toLowerCase"][i % 2]]()
    )
  );
}

const weird = s => {return s.replace(/(\S{0,1})\S/g, x=>`${x[0].toUpperCase()}${(x[1]||'').toLowerCase()}`)}

function toWeirdCase(str) {
  const s = str.split("");
  let f = true;
  return s.reduce((acc, cur) => {
    cur !== " " ? ((cur = f ? cur.toUpperCase() : cur.toLowerCase()), (f = !f)) : (f = true);
    return acc + cur;
  }, "");
}
 
console.log(toWeirdCase("  abcde  fgqwe    treydfg")); //   AbCdE  FgQwE    TrEyDfG