Parallel Ajax Calls in Javascript/jQuery

Question

I am completely new to Javascript/jquery world and need some help. Right now, I am writing one html page where I have to make 5 different Ajax calls to get the data to plot grap

Answer 1

It looks like you need to dispatch your request asynchronously and define a callback function to get the response.

The way you did, it'll wait until the variable is successfully assigned (meaning: the response has just arrived) until it proceeds to dispatch the next request. Just use something like this.

$.ajax({
  url: url,
  dataType: 'json',
  data: data,
  success: function(data) {
     area0Obj = data;
  }
});

This should do the trick.

Answer 2

The following worked for me - I had multiple ajax calls with the need to pass a serialised object:

    var args1 = {
        "table": "users",
        "order": " ORDER BY id DESC ",
        "local_domain":""
    }
    var args2 = {
        "table": "parts",
        "order": " ORDER BY date DESC ",
        "local_domain":""
    }

    $.when(
        $.ajax({
                url: args1.local_domain + '/my/restful',
                headers: {
                    'Content-Type': 'application/x-www-form-urlencoded'
                },
                type: "POST",
                dataType : "json",
                contentType: "application/json; charset=utf-8",
                data : JSON.stringify(args1),
                error: function(err1) {
                    alert('(Call 1)An error just happened...' + JSON.stringify(err1));
                }
            }),
        $.ajax({
            url: args2.local_domain + '/my/restful',
            headers: {
                'Content-Type': 'application/x-www-form-urlencoded'
            },
            type: "POST",
            dataType : "json",
            contentType: "application/json; charset=utf-8",
            data : JSON.stringify(args2),
            error: function(err2) {
                calert('(Call 2)An error just happened...' + JSON.stringify(err2));
            }
        })                     

    ).then(function( data1, data2 ) {
        data1 = cleanDataString(data1);
        data2 = cleanDataString(data2);

        data1.forEach(function(e){
            console.log("ids" + e.id)
        });
        data2.forEach(function(e){
            console.log("dates" + e.date)
        });

    })

    function cleanDataString(data){
            data = decodeURIComponent(data);
            // next if statement was only used because I got additional object on the back of my JSON object
            // parsed it out while serialised and then added back closing 2 brackets
            if(data !== undefined && data.toString().includes('}],success,')){ 
                temp = data.toString().split('}],success,');
                data = temp[0] + '}]';
            }
            data = JSON.parse(data);
            return data;                    // return parsed object
      }

Answer 3

you may combine all the functionality of the different ajax functions into 1 ajax function, or from 1 ajax function, call the other functions (they would be private/controller side in this case) and then return the result. Ajax calls do stall a bit, so minimizing them is the way to go.

you can also make the ajax functions asynchronous (which then would behave like normal functions), then you can render the graph at the end, after all the functions return their data.