题解 | #数组过滤#

let fragment = document.createDocumentFragment();
select.onchange = function() {
    let value = this.value;
    showList(value);
}

function showList(filterItem) {
    ul.innerHTML = '';
    let fn;
    let data = [];
    switch (filterItem) {
        case '1':
            fn = item => item.sales <= 100;
            break;
        case '2':
            fn = item => item.sales < 500 && item.sales > 100;
            break;
        case '3':
            fn = item => item.sales >= 500;
            break;
    }

    if (filterItem === '0') {
        data = cups;
    } else {
        data = cups.filter(fn);
    }
    data.map(item => {
        let li = document.createElement('li');
        li.innerText = item.name;
        fragment.appendChild(li);
    })
    ul.appendChild(fragment);
}