为什么.then（）中的value未定义链接到Promise？

因为没有ed

Promise

return

.then()

Promise

请注意，

.then()

Promise

解决方案是

return

return

Promise

.then()

function doStuff(n ) {  return new Promise(function(resolve, reject) {    setTimeout(function() {      resolve(n * 10)    }, Math.floor(Math.random() * 1000))  })  .then(function(result) {    if (result > 100) {      console.log(result + " is greater than 100")    } else {      console.log(result + " is not greater than 100");    }    // `return` `result` or other value here    // to avoid `undefined` at chained `.then()`    return result  })}doStuff(9).then(function(data) {  console.log("data is: " + data) // `data` is not `undefined`});