js如何将字符串转成数组对象

"1,2,3"变成[{content:1},{content:2},{content:3}]

第一种写法
let str = "1,2,3";
let arr = [];
let s1 = str.split(',');
s1.map((item) => {
  let obj = {};
    obj.content = item;
    arr.push(obj);
  })
console.log(arr)

第二种写法
let str = "1,2,3"
let arr = str.split(",").map((item)=>{
  for(let i = 0;i<str.length;i++){
    let obj = {};
    obj.content = item;
    return obj
  }
})
console.log(arr) //打印结果如下

第三种写法
let str = "1,2,3";
let arr = str.split(",");
for(let i = 0;i<arr.length;i++){
  arr[i] = { content: arr[i]};
}
console.log(arr)