多个Ajax异步调用

Question

I have list of lib name from the name I want fetch the author name. for this I made each loop on library name and make async call. I want return all the author name with library name once the call was end. While I try with Async call it return the call back before the call was successes. so I have try to return the callback in success but now the call back was return once the first request completed. I have try with sync call but it block the user interface. so what is the best method to do that. My code

function FetchLibAuthorID(LibCollection, callback) {
$.each(LibCollection, function (key, value) {
    $.ajax({
        url: value.MetadataURI + '?$select=schemaXml',
        type: "GET",
        headers: { "Accept": "application/json;odata=verbose" },
        success: function (data) {
            var listProperties = schemaXml2Json(data.d.SchemaXml);
            LibCollection[key].AuthorID = listProperties.Author;
            LibCollection[key].RootFolder = listProperties.RootFolder;
        },
        error: function (data2) {
            alert('error');
        }
    });
});
return callback(LibCollection);

}

Answer 1

var libCollection = [{ MetadataURI: "url1" }, { MetadataURI: "url2" }];

function loadLibrary(complete) {
    if (libCollection.length === 0) {
        complete();
        return;
    }

    var lib = libCollection.pop();
    $.ajax({
        url: lib.MetadataURI + '?$select=schemaXml',
        type: "GET",
        headers: { "Accept": "application/json;odata=verbose" },
        complete: function (data) {
            var listProperties = schemaXml2Json(data.d.SchemaXml);
            LibCollection[key].AuthorID = listProperties.Author;
            LibCollection[key].RootFolder = listProperties.RootFolder;

            loadLibrary(complete);
        }
    });
};

// call the function

loadLibrary(function() {
    alert("all libraries have been loaded")
});