console.info([...Array(50000).keys()])
console.info([...Array(50000).keys()].map((v, i) => ({
shopCode: v
})));
console.info(Object.keys(window).slice(0,100));
console.info(Array.apply(null,Array(100)))
console.log([1,2].keys().next())
console.log([1,2][Symbol.iterator]().next())
console.log([].values===[][Symbol.iterator])
Array(100) 只有长度没有元素和索引的空数组
[].keys() 得到数组的包含数组键的可迭代对象