SOURCE

 let arr = [{
        id: 1,
        name: '张一',
        age: 25,
        class: '一班'
    }, {
        id: 2,
        name: '张二',
        age: 25,
        class: '二班'
    }, {
        id: 4,
        name: '张三',
        age: 25,
        class: '三班'
    }]
    let obj = arr.find(item => item.id == 1)
    console.log(obj); 
    // 结果：{id: 1, name: '张一', age: 25, class: '一班'}

    let obj1 = arr.find((item,index) => 
    { 
        let retItem;
        if(item.id == 2)
        {
            retItem=item;
            console.log(index);
        }
        
        return retItem;
    })
    console.log(obj1);