js 单词的首字母大写

function titleCase(str) {
    
    
  let strArr = str.split(" ");
  strArr = strArr.map((x) => {
    
    
    x = x.toLowerCase();
    let xArr = x.split("");
    xArr[0] = xArr[0].toUpperCase();

    return x = xArr.join("");
  })
  return strArr.join(" ");
}

titleCase("HERE IS MY HANDLE HERE IS MY SPOUT");