jQuery何时完成

Question

I am trying to validate a field off of two calls to the database. it goes to the database and validates if its true or false. I need to chain a few AJAX calls to do this. I am using .when, .then, and .done to do this, but it doesn't seem to be working.

var Validate = function () {
        var isValid = true;
        $errorList.find('li').remove();
        $lblAError.text('');

        $.when(ParcelValidate(isValid))
            .then(AccountValidate(isValid))
            .done(function () {
            return isValid
        });
    };

    var ParcelValidate = function (isValid) {
        return $.ajax({
            url: "../WebServices/ParcelMasterWebService.asmx/IsParcelActive",
            method: "POST",
            data: JSON.stringify({ "pin": $parcID.val() }),
            contentType: 'application/json; charset=utf-8',
            datatype: 'json',
            success: function (data) {
                if (!data.d) {
                    isValid = false;
                    $lblPError.text('!').css(({ "color": "red" }));
                    $errorList.append('<li>Parcel must be on record.</li>').css(({ "color": "red" }));
                }
            },
            fail: function () {
                isValid = false;
                $lblPError.text('!').css(({ "color": "red" }));
                $errorList.append('<li>Unexpected error occured!</li>').css(({ "color": "red" }));
            }
        })
    }
    var AccountValidate = function (isValid) {
        return $.ajax({
            url: "../WebServices/FireProtectMasterWebService.asmx/isAccountActive",
            method: "POST",
            data: JSON.stringify({ "accountID": $parcID.val() }),
            contentType: 'application/json; charset=utf-8',
            datatype: 'json',
            success: function (data) {
                if (data.d) {
                    isValid = false;
                    $lblPError.text('!').css(({ "color": "red" }));
                    $errorList.append('<li>Cannot have duplicate Parcels.</li>').css(({ "color": "red" }));
                }
            },
            fail: function () {
                isValid = false;
                $lblPError.text('!').css(({ "color": "red" }));
                $errorList.append('<li>Unexpected error occured!</li>').css(({ "color": "red" }));
            }
        })
    }

Answer 1

You have a couple of issues, the first one is that the is that the validate function is not returning anything, since you are making asynchronous call your function should return a promise and instead of returning a boolean it would be better to reject/resolve this promise, your code would look like this:

var Validate = function () {
    $errorList.find('li').remove();
    $lblAError.text('');
    var promise = $.Deferred();

    ParcelValidate(promise).then(AccountValidate(promise));

    return promise;
};

var ParcelValidate = function (promise) {
    return $.ajax({
        url: "../WebServices/ParcelMasterWebService.asmx/IsParcelActive",
        method: "POST",
        data: JSON.stringify({ "pin": $parcID.val() }),
        contentType: 'application/json; charset=utf-8',
        datatype: 'json',
        success: function (data) {
            if (!data.d) {
                $lblPError.text('!').css(({ "color": "red" }));
                $errorList.append('<li>Parcel must be on record.</li>').css(({ "color": "red" }));
                promise.reject(false);
            }
        },
        fail: function () {
            $lblPError.text('!').css(({ "color": "red" }));
            $errorList.append('<li>Unexpected error occured!</li>').css(({ "color": "red" }));
            promise.reject(false);
        }
    })
}
var AccountValidate = function (promise) {
    return $.ajax({
        url: "../WebServices/FireProtectMasterWebService.asmx/isAccountActive",
        method: "POST",
        data: JSON.stringify({ "accountID": $parcID.val() }),
        contentType: 'application/json; charset=utf-8',
        datatype: 'json',
        success: function (data) {
            if (data.d) {
                $lblPError.text('!').css(({ "color": "red" }));
                $errorList.append('<li>Cannot have duplicate Parcels.</li>').css(({ "color": "red" }));
                promise.reject(false);
            }
            promise.resolve(true);
        },
        fail: function () {
            $lblPError.text('!').css(({ "color": "red" }));
            $errorList.append('<li>Unexpected error occured!</li>').css(({ "color": "red" }));
            promise.reject(false);
        }
    })
}

Now whatever is calling validate should wait for the promise and react accordingly to the done/fail methods ie:

Validate().done(function(){/*valid*/}).fail(function(){/*not valid*/})

One last thing as it is your code right now, since you are passing the isValid as a parameter, changing the value would not modify the isValid value of the original function.