一個用於處理所有異步請求的最佳解決方案是「無極」。
Promise對象表示異步操作的最終完成(或失敗)。
例子:
let myFirstPromise = new Promise((resolve, reject) => {
// We call resolve(...) when what we were doing asynchronously was successful, and reject(...) when it failed.
// In this example, we use setTimeout(...) to simulate async code.
// In reality, you will probably be using something like XHR or an HTML5 API.
setTimeout(function(){
resolve("Success!"); // Yay! Everything went well!
}, 250);
});
myFirstPromise.then((successMessage) => {
// successMessage is whatever we passed in the resolve(...) function above.
// It doesn't have to be a string, but if it is only a succeed message, it probably will be.
console.log("Yay! " + successMessage);
});
Promise
如果你有3個異步函數和期待,爲了運行,操作如下:
let FirstPromise = new Promise((resolve, reject) => {
FirstPromise.resolve("First!");
});
let SecondPromise = new Promise((resolve, reject) => {
});
let ThirdPromise = new Promise((resolve, reject) => {
});
FirstPromise.then((successMessage) => {
jQuery.ajax({
type: "type",
url: "url",
success: function(response){
console.log("First! ");
SecondPromise.resolve("Second!");
},
error: function() {
//handle your error
}
});
});
SecondPromise.then((successMessage) => {
jQuery.ajax({
type: "type",
url: "url",
success: function(response){
console.log("Second! ");
ThirdPromise.resolve("Third!");
},
error: function() {
//handle your error
}
});
});
ThirdPromise.then((successMessage) => {
jQuery.ajax({
type: "type",
url: "url",
success: function(response){
console.log("Third! ");
},
error: function() {
//handle your error
}
});
});
通過這種方法,您可以根據需要處理所有異步操作。
Promise是處理所有異步請求的最佳對象。 [使用Promise對象修復異步請求](https://stackoverflow.com/a/47719849/7487135) – 2017-12-08 18:03:01