js把每个词的首字母转大写

先看效果图

 1 //把首字母变大写
 2     function firstToUpperCase(id) {
 3         var str=document.getElementById(id).value;
 4         //通过“空格”符来分割成数组
 5         var arr=str.toLowerCase().split(" ");// ["aq","","tn"]
 6         let neweArr=[];
 7         for (var i=0; i<arr.length;i++) {
 8             if (arr[i]!="") {// 不为空则把首字母大写，后面的截取出来不变
 9                 //arr[i][0] 相当于二维数组了 ["aq"]=>["Aq"]
10                 neweArr.push(arr[i][0].toUpperCase()+arr[i].substr(1));
11             }else {
12                 neweArr.push(arr[i]);
13             }
14         }
15         var showArr=neweArr.join(" ");
16         document.getElementById(id).value=showArr;
17     }

<input onkeyup="firstToUpperCase(this.id)"  type="text" class="form-control" id="userNameEn" name="userNameEn" placeholder="如:Linda Wang"  value="${model.userNameEn}">