Promise Error Handling

上图53产生结果为

caugh by .catch Error: Unauthorized access to the user data

if try catch in promise

Summary:

promise error couldn't catch by try-catch
Inside the promise, the promise.catch() method will catch the error caused by the throw statement and reject().
If an error occurs and you don’t have the promise.catch() method, the JavaScript engine issues a runtime error and stops the program.
try-catch will catch error inside a promise, and not delegated it out the promise. try-catch并不会把错误再往上传递出去
下方效果相同, 区别是await会阻塞等待, 但是promise.then不会:

// 等待 b() 执行完, 才执行后续的代码
const a = await b()

// 该函数执行后, 马上执行后面的代码, 再回头异步完成执行 then() 里面的方法
b()
 .then(a => ...)
 .catch(err => ...)