数组利用reduce()求和问题

Question

var datas = [
    {
        name: '张',
        sex: 'female',
        age: 30
    },
    {
        name: '李',
        sex: 'male',
        age: 20
    },
    {
        name: '王',
        sex: 'female',
        age: 40
    }
];

不用for,map(),怎样利用reduce()求age的和

Answer 1

datas.reduce(function(pre, next) {
    return pre + next.age;
}, 0);