jQuery $ .wait（）用于* all * deferred的被拒绝？

Question

jQuery具有Deferred API的好功能，$.wait()可与多个Deferred s/Promise s一起使用。它返回时：

• 所有Deferred S的已经resolve() d

或

• 其中Deferred S的一直reject()版

大多数时候这是你想要的，但有时候你想知道什么时候全部是其中有reject() ed。

有没有简单或优雅的方式来做类似$.wait()但只有当所有Deferred s都被拒绝？

（可能还有其他的用例，但我的是这与waiting for the first of several Deferred's to resolve结合起来。）

Answer 1

在如何无极规范很可能对未来有PromiseInspection对象会精神，这里有一个jQuery的添加 - 功能上，告诉你，当所有的承诺都做了，是否履行或拒绝：

// 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); 
    } 

    function PromiseInspection(fulfilled, val) { 
     return { 
      isFulfilled: function() { 
       return fulfilled; 
      }, value: function() { 
       return fulfilled ? val: undefined; 
      }, reason: function() { 
       return !fulfilled ? val: undefined; 
      } 
     }; 
    } 
    return $.when.apply($, args.map(function(p) { 
     // if incoming value, not a promise, then wrap it in a promise 
     if (!p || (!(typeof p === "object" || typeof p === "function")) || typeof p.then !== "function") { 
      p = $.Deferred().resolve(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 
      // this is required in jQuery 1.x and 2.x (works in jQuery 3.x, but the extra .resolve() is not required in 3.x) 
      return $.Deferred().resolve(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); 
    }); 
} 

然后，您可以使用它像这样：

$.settle(promiseArray).then(function(inspectionArray) { 
    inspectionArray.forEach(function(pi) { 
     if (pi.isFulfilled()) { 
      // pi.value() is the value of the fulfilled promise 
     } else { 
      // pi.reason() is the reason for the rejection 
     } 
    }); 
}); 

请记住，$.settle()将始终满足（永不拒绝），并且履行的值是一个PromiseInspection对象的数组，您可以询问每个对象以查看它是否被满足或拒绝，然后获取相应的值或原因。请参见下面的演示，例如使用：

工作演示：https://jsfiddle.net/jfriend00/y0gjs31r/