js将字符串中的每一个单词的首字母变为大写其余均为小写

function titleCase(str) { var newarr,newarr1=[];  newarr = str . toLowerCase() . split(" "); for(var i = 0 ; i < newarr . length ; i++){ newarr1 . push(newarr[i][0] . toUpperCase()+newarr[i] . substring(1)); } return newarr1.join(' ');}titleCase("I'm a little tea pot");

function titleCase(str) { var newarr,newarr1;  newarr =str.toLowerCase().split(" "); for(var i=0;i<newarr.length;i++){ newarr[i] = newarr[i][0].toUpperCase()+newarr[i].substring(1,newarr[i].length)); } newarr1 = newarr.join(" "); return newarr1;}titleCase("I'm a little tea pot");