How to use the Promise function of JavaScript
This article mainly introduces the relevant knowledge of "how to use the Promise function of JavaScript". The editor shows you the operation process through an actual case. The method of operation is simple and fast, and it is practical. I hope this article "how to use the Promise function of JavaScript" can help you solve the problem.
Promise function
The timer program looks longer than a function waterfall, so we can write its core as a Promise function:
Case study
Function print (delay, message) {
Return new Promise (function (resolve, reject) {
SetTimeout (function () {
Console.log (message)
Resolve ()
}, delay)
})
}
Then we can rest assured to boldly implement the program function:
Case study
Print (1000, "First") .then (function () {
Return print (4000, "Second")
}) .then (function () {
Print (3000, "Third")
})
The function whose return value is a Promise object is called the Promise function, which is often used to develop libraries based on asynchronous operations.
This is the end of the content about "how to use the Promise function of JavaScript". Thank you for reading. If you want to know more about the industry, you can follow the industry information channel. The editor will update different knowledge points for you every day.
