使用jquery时,多个ajax请求$
在jquery上为不同的ajax使用$.when有一些缺点。成功处理ajax调用非常好。但是,如果一个请求失败,您将无法在另一个请求中获取其他数据 前 var ajax1Success=function(){ 返回$.ajax(…); }; var ajax2Success=function(){ 返回$.ajax(…); }; var ajax3BoundtoFail=函数(){ 返回$.ajax(…); }; $.when(ajax1Succes()、ajax2Success()、ajax3BoundtoFail()).done(函数(a1、a2、a3){ //一切都好 }).fail(函数(){ //不好…ajax3肯定会失败 }); 如何从成功的ajax请求中获取其他数据,有什么好的解决方案吗?使用jquery时,多个ajax请求$,jquery,ajax,jquery-deferred,Jquery,Ajax,Jquery Deferred,在jquery上为不同的ajax使用$.when有一些缺点。成功处理ajax调用非常好。但是,如果一个请求失败,您将无法在另一个请求中获取其他数据 前 var ajax1Success=function(){ 返回$.ajax(…); }; var ajax2Success=function(){ 返回$.ajax(…); }; var ajax3BoundtoFail=函数(){ 返回$.ajax(…); }; $.when(ajax1Succes()、ajax2Success()、ajax3
$。when()
具有“fail fast”设计。这意味着第一个承诺失败会导致$.when()
拒绝,而您只会得到拒绝信息。从jQuery文档:
该方法将在所有
延迟解决,或在其中一个
延期被拒绝
但是,您可以使用不同类型的函数来监视您的承诺组。这种类型的功能通常被称为“结算”,在这里,您等待所有承诺结算,并且您从所有承诺中获得结果,无论这些承诺是得到解决还是被拒绝
下面是我在过去使用过的jQuery promies的实现,您可以这样使用:
$.settle([ajax1Succes(), ajax2Success(), ajax3BoundtoFail()]).then(function(results) {
// results is an array of PromiseInspection Objects
// for each of them, you can see if the corresponding promise
// succeeded with a value or failed with an error
results.forEach(function(pi, index) {
if (pi.isFulfilled()) {
console.log("Promise #" + (index + 1) + " succeeded with result " + pi.value());
} else {
console.log("Promise #" + (index + 1) + " failed with reason " + pi.reason());
}
});
});
或者,如果不需要确切的错误,可以使用更简单的版本:
$.settleVal(null, [ajax1Succes(), ajax2Success(), ajax3BoundtoFail()]).then(function(results) {
// results contains the results from all the successful promises
// any promises that has an error will show null as the result
});
请注意,它们使用的接口更像标准的Promise.all()
,它们接受一系列承诺并解析为一系列结果,因为这通常更易于在现实世界中使用
下面是实现:
(function() {
function isPromise(p) {
return p && (typeof p === "object" || typeof p === "function") && typeof p.then === "function";
}
function wrapInPromise(p) {
if (!isPromise(p)) {
p = $.Deferred().resolve(p);
}
return p;
}
function PromiseInspection(fulfilled, val) {
return {
isFulfilled: function() {
return fulfilled;
}, isRejected: function() {
return !fulfilled;
}, isPending: function() {
// PromiseInspection objects created here are never pending
return false;
}, value: function() {
if (!fulfilled) {
throw new Error("Can't call .value() on a promise that is not fulfilled");
}
return val;
}, reason: function() {
if (fulfilled) {
throw new Error("Can't call .reason() on a promise that is fulfilled");
}
return val;
}
};
}
// pass either multiple promises as separate arguments or an array of promises
$.settle = function(p1) {
var args;
if (Array.isArray(p1)) {
args = p1;
} else {
args = Array.prototype.slice.call(arguments);
}
return $.when.apply($, args.map(function(p) {
// make sure p is a promise (it could be just a value)
p = wrapInPromise(p);
// Now we know for sure that p is a promise
// Make sure that the returned promise here is always resolved with a PromiseInspection object, never rejected
return p.then(function(val) {
return new PromiseInspection(true, val);
}, function(reason) {
// convert rejected promise into resolved promise by returning a resolved promised
// One could just return the promiseInspection object directly if jQuery was
// Promise spec compliant, but jQuery 1.x and 2.x are not so we have to take this extra step
return wrapInPromise(new PromiseInspection(false, reason));
});
})).then(function() {
// return an array of results which is just more convenient to work with
// than the separate arguments that $.when() would normally return
return Array.prototype.slice.call(arguments);
});
}
// simpler version that just converts any failed promises
// to a resolved value of what is passed in, so the caller can just skip
// any of those values in the returned values array
// Typically, the caller would pass in null or 0 or an empty object
$.settleVal = function(errorVal, p1) {
var args;
if (Array.isArray(p1)) {
args = p1;
} else {
args = Array.prototype.slice.call(arguments, 1);
}
return $.when.apply($, args.map(function(p) {
p = wrapInPromise(p);
return p.then(null, function(err) {
return wrapInPromise(errorVal);
});
}));
}
})();
(function() {
function isPromise(p) {
return p && (typeof p === "object" || typeof p === "function") && typeof p.then === "function";
}
function wrapInPromise(p) {
if (!isPromise(p)) {
p = $.Deferred().resolve(p);
}
return p;
}
function PromiseInspection(fulfilled, val) {
return {
isFulfilled: function() {
return fulfilled;
}, isRejected: function() {
return !fulfilled;
}, isPending: function() {
// PromiseInspection objects created here are never pending
return false;
}, value: function() {
if (!fulfilled) {
throw new Error("Can't call .value() on a promise that is not fulfilled");
}
return val;
}, reason: function() {
if (fulfilled) {
throw new Error("Can't call .reason() on a promise that is fulfilled");
}
return val;
}
};
}
// pass either multiple promises as separate arguments or an array of promises
$.settle = function(p1) {
var args;
if (Array.isArray(p1)) {
args = p1;
} else {
args = Array.prototype.slice.call(arguments);
}
return $.when.apply($, args.map(function(p) {
// make sure p is a promise (it could be just a value)
p = wrapInPromise(p);
// Now we know for sure that p is a promise
// Make sure that the returned promise here is always resolved with a PromiseInspection object, never rejected
return p.then(function(val) {
return new PromiseInspection(true, val);
}, function(reason) {
// convert rejected promise into resolved promise by returning a resolved promised
// One could just return the promiseInspection object directly if jQuery was
// Promise spec compliant, but jQuery 1.x and 2.x are not so we have to take this extra step
return wrapInPromise(new PromiseInspection(false, reason));
});
})).then(function() {
// return an array of results which is just more convenient to work with
// than the separate arguments that $.when() would normally return
return Array.prototype.slice.call(arguments);
});
}
// simpler version that just converts any failed promises
// to a resolved value of what is passed in, so the caller can just skip
// any of those values in the returned values array
// Typically, the caller would pass in null or 0 or an empty object
$.settleVal = function(errorVal, p1) {
var args;
if (Array.isArray(p1)) {
args = p1;
} else {
args = Array.prototype.slice.call(arguments, 1);
}
return $.when.apply($, args.map(function(p) {
p = wrapInPromise(p);
return p.then(null, function(err) {
return wrapInPromise(errorVal);
});
}));
}
})();