promise
Resolve and reject are both functions.
The executor function is a synchronous callback function
then
Then is a method, a method of an instance object
The correct way to write it is p.teng
catch
The catch method is of the instance object
So promise.catch() is wrong
Catch is a callback function used to return a failure
Similar to the second callback function in p.Teng (()=>{},()=>{})
resolve
Methods are function objects, promise.resolve() is correct
Function: Converts a value to a Promise object
This is a big pity. Promise has three state values: fulfilled state
Rejected: Indicates the failed state
Pending: Indicates the pending status
PromiseState: This property is in the promise state
PromiseResult: This property is the result of a promise
The result value is not the same as the return value
reject
A method is the method of a function object, promise.reject()
Action: Converts a value to a failed promise object
Reject (reject) The final result is rejected
When the resolve and reject functions are called, the default state of promise is changed to fulfilled and Rejected, and the result value is changed to success or failure
Unfinished…