var equipValue = new Array();
 var selectedTrucks  = new Array();

for (var i in selectedTrucks) {
    (function(i){
        // Simple Ajax request that return me a Json values
        var ajaxUrl = '/ajaxRequest/getSingleTruckPosition/' + selectedTrucks[i];

        $.ajax({
            url: ajaxUrl,
        })
        .done(function(data) {
            if(data != null){
                //  equipValue doens't go.
                // Unable to set property '0' of undefined or null reference
                equipValue[i] = jQuery.parseJSON(data);
             }
         });

done((function(data) {
            if(data != null){
                //  equipValue doens't go.
                // Unable to set property '0' of undefined or null reference
                equipValue[i] = jQuery.parseJSON(data);
             }
         }).bind(this));