使用异步Ajax调用构建对象

Question

我需要返回一个依赖多个异步jquery ajax调用的自定义对象。

下面的示例代码：

function BuildMyObject() {
    var bp = null;
    var accountId = getAccountId();
    var signature = getSignature();
    var transactionType = getTransactionType();
    var mode = getMode();
    var merchantIdentifier = getMerchantIdentifier();
    jQuery.when(accountId, signature, transactionType, mode, merchantIdentifier).done(function(rAcctId,
        rSig,
        rTransType,
        rMode,
        rMerchId) {
        bp = new MyObject(
            rAcctId[0],
            rSig[0],
            rTransType[0],
            rMode[0],
            rMerchId[0]);
    });
    return bp;
}

现在，它返回null； 因为return语句在异步调用完成之前触发。 有没有办法等到所有调用完成后再返回对象？ 如果我将ajax调用设置为synchronous，则它可以工作； 但我想避免这种情况。

Answer 1

您可以针对异步功能的场景使用Promises或回调

 //callback example function BuildMyObject(callback) { var bp = null; var accountId = getAccountId(); var signature = getSignature(); var transactionType = getTransactionType(); var mode = getMode(); var merchantIdentifier = getMerchantIdentifier(); jQuery.when(accountId, signature, transactionType, mode, merchantIdentifier).done(function(rAcctId, rSig, rTransType, rMode, rMerchId) { bp = new MyObject( rAcctId[0], rSig[0], rTransType[0], rMode[0], rMerchId[0]); ) callback(bp) }); } //or with promise function BuildMyObject() { return new Promise((resolve,reject) =>{ var bp = null; var accountId = getAccountId(); var signature = getSignature(); var transactionType = getTransactionType(); var mode = getMode(); var merchantIdentifier = getMerchantIdentifier(); jQuery.when(accountId, signature, transactionType, mode, merchantIdentifier).done(function(rAcctId, rSig, rTransType, rMode, rMerchId) { bp = new MyObject( rAcctId[0], rSig[0], rTransType[0], rMode[0], rMerchId[0]); ) resolve(bp) }); }) } BuildMyObject() .then((bp) =>{ //do somthing with bp })