1460911346229.js

var orginalData = [{name:'jch', age:30, score:90, sex: 1, lesson: 'math'},{ name:'oh', age:31, score: 80, sex:1, lesson: 'math'}, {name:'jia', age:27, score: 70, sex:0, lesson: 'math'}, {name:'jch', age: 30, score: 80, sex: 1, lesson: 'english'}];

const fn_01 = (data, specifiedAge) => data.filter(item => item.age > specifiedAge);

const fn_02 = (data, specifiedAge) => data.reduce((prev, curr) => {
    if (curr.age > specifiedAge) {
        prev.name.push(curr.name);
        prev.lesson.push(curr.lesson);
    }
    return prev;
}, {name: [], lesson: []});

const fn_03 = (data) => data.reduce((prev, curr, i, data) => {
    prev.avr_lesson += curr.score;
    prev.avr_sex += curr.score;
    if (i === data.length - 1) { // when finish the accumulation
        prev.avr_lesson = prev.avr_lesson / data.length;
        prev.avr_sex = prev.avr_sex / data.length;
    }
    return prev;
}, {avr_lesson: 0, avr_sex: 0});


console.log('fn_01', fn_01(orginalData, 28));
console.log('fn_02', fn_02(orginalData, 28));
console.log('fn_03', fn_03(orginalData));