题解 | #数组过滤#,策略模式

var cups = [
                { type: 1, price: 100, color: 'black', sales: 60, name: '牛客logo马克杯' },
                { type: 2, price: 40, color: 'blue', sales: 100, name: '无盖星空杯' },
                { type: 4, price: 60, color: 'green', sales: 200, name: '老式茶杯' },
                { type: 3, price: 50, color: 'green', sales: 600, name: '欧式印花杯' }
            ]
            var select = document.querySelector('select');
            var ul = document.querySelector('ul');
            // 补全代码
            let obj = {
                0:()=>[].concat(cups),
                1:()=>cups.filter(item=>item.sales<100),
                2:()=>cups.filter(item=>item.sales>=100&&item.sales<=500),
                3:()=>cups.filter(item=>item.sales>500)
            }
            select.onchange = function(e){
                let srr = obj[select.value]();
                let len = srr.length;
                if(!len)return;
                let fragment = document.createDocumentFragment();
                for(let i = 0; i<len;i++){
                    let li = document.createElement('li');
                    li.innerText = srr[i].name;
                    fragment.appendChild(li)
                }
                ul.innerHTML = '';
                ul.appendChild(fragment)
                
            }