Question

I have a need to collect data from multiple sources (xml or JSON format) via AJAX, and then run a function that consumes these data sets.

How can I check that all the AJAX calls are successful before the function is executed? Ideally, I’d like to keep async calls to minimize the response time.

Answer 1

Conceptually, it would work like this:

1. Use async calls.
2. Code a success handler for each call.
3. When a call succeeds, you store the data from it in some common place and then record that this call has finished.
4. At the end of each success handler, you check to see if all data is available now and, if so, you can a function to consume it.

Some pseudo code for an ajax call:

results = [];
$.ajax({
   // other parameters here
    success: function(data) {
        results.push(data);
        checkResults();
    };
});

function checkResults() {
    // if all five results are in, then we're ready to process them
    if (results.length >= 5) {
         processResults(results);
    }
}