例子：

let list=[
    {
        id:1,
        name:'zhangsan'
    },
    {
        id:2,
        name:'zhangsan'
    },
    {
        id:3,
        name:'zhangsan'
    },
    {
        id:4,
        name:'zhangsan'
    }
]
function getNames(list) {
    let arr = [];
    list.forEach( (item, index) => {
        arr.push(item.name);
    })
    return arr;
},