Question

I have declared global variable named counter=0 on my index.html page inside head section

<script>
var counter=0;
</script>

now in my one of function i am setting its value as

    function getCounter(param)
    {
        $.getJSON("somewebserviceURL&format=json&callback=?",
            function(data)
            {
                 $.each(data, function(i, item)
                    {
                        counter++;
                    });

            });
//I am not able to get the latest value here & in upcoming functions which use this variable
         alert(counter);

    }

Answer 1

This is because getJSON is asynchronous. This means the counter variable will not have been incremented before alert(counter) is hit. Instead, move the alert to just after your $.each() loop:

function getCounter(param) {
    $.getJSON(
        "somewebserviceURL&format=json&callback=?",
        function(data) {
            $.each(data, function(i, item) {
                counter++;
            });
            alert(counter);
        }
    );
}