美团到店一面
1、看输出
setTimeout(() => { console.log(2) Promise.resolve().then(() => { console.log(3) }) }) new Promise((resolve) => { console.log(4) setTimeout(() => { console.log(5) resolve(); }, 2); }).then(res => { console.log(res) });
2、数组扁平化,能控制扁平化层级
array.flat(arr, dep)
[1, [2, [ 3, 4]]]
[1, 2, [3, 4]]