题目描述为什么下面两段代码，执行顺序会不同相关代码function light(color, second) { return new Promise((resolve, reject) => { setTimeout(() => { console.log(color) resolve() }, second * 1000) })}let list = [ { color: 'red', time: 3 }, { color: 'green', time: 2 }, { color: 'yellew', time: 1 }]function orderLights(list) { let promise = Promise.resolve() list.forEach(item => { // promise.then(function() { // return light(item.color, item.time) // }) promise = promise.then(function () { return light(item.color, item.time) }) })}orderLights(list)