如何从内部拒绝承诺然后起作用 [英] How to reject a promise from inside then function

问题描述

这可能是一个愚蠢的问题，但是在诺言链中间，您如何从then函数之一内部拒绝诺言呢?例如:

This is probably a silly question, but mid promise chain, how do you reject a promise from inside one of the then functions? For example:

someActionThatReturnsAPromise()
    .then(function(resource) {
        return modifyResource(resource)
    })
    .then(function(modifiedResource) {
        if (!isValid(modifiedResource)) {
            var validationError = getValidationError(modifiedResource);
            // fail promise with validationError
        }
    })
    .catch(function() {
        // oh noes
    });

不再有对原始解析/拒绝函数或PromiseResolver的引用.我只是应该添加 return Promise.reject(validationError); 吗?

There's no longer a reference to the original resolve/reject function or the PromiseResolver. Am I just supposed to add return Promise.reject(validationError); ?

推荐答案

我只是应该添加 return Promise.reject(validationError); ?

是的.但是，它是如此复杂，仅在jQuery中，并带有 Promise/A + 兼容的库，您也可以简单地

Yes. However, it's that complicated only in jQuery, with a Promise/A+-compliant library you also could simply

throw validationError;

因此您的代码将如下所示

So your code would then look like

someActionThatReturnsAPromise()
    .then(modifyResource)
    .then(function(modifiedResource) {
        if (!isValid(modifiedResource))
            throw getValidationError(modifiedResource);
        // else !
        return modifiedResource;
    })
    .catch(function() {
        // oh noes
    });

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