Use try, catch when querytask times out using JS API

Question

When I do a querytask and the date range criteria used is too vast, I get a 500 internal server error after 1.7 minutes every time (unless the query takes less than 1.7 minutes, then it runs fine). Is there any way I can use try, catch to let the user know the search has timed out.

I tried the following try, catch code but it does not do anything. It still says "Searching..." in my 'wait' div.

 function execute () {
 query.geometry = addressPoint;
 startDateQuery = document.getElementById("startDate").value
 endDateQuery = document.getElementById("endDate").value
 //esriConfig.defaults.io.timeout = 60,000;
 if (endDateQuery !== null && endDateQuery !== undefined && endDateQuery !== ""){
 query.where = "(DATE_VAL >= '" + startDateQuery + "') AND (DATE_VAL <= '" + endDateQuery + "')";
 }
 else {
 query.where = "DATE_VAL = '" + startDateQuery + "'";
 }
 try{
 queryTask.execute(query, showResults);
 document.getElementById('wait').innerHTML = "Searching...";
 }
 catch(err) {
 document.getElementById('wait').innerHTML = "Search timed out. Use a smaller search range.";
 }
 }

Answer 1

You would not have to define a try/catch statement. The QueryTask includes an error callback. You could just define that function and insert your code into it:

queryTask.execute(query, showResults, errCallback);
function errCallback(){
 document.getElementById('wait').innerHTML = "Search timed out. Use a smaller search range.";
}

Answer 2

The third parameter a QueryTask takes is a handler for error

try catch is not reliable in JavaScript because of its async nature

do it this way

queryTask.execute(query, showResults, function(){
 document.getElementById('wait').innerHTML = "Search timed out. Use a smaller search range.";
});

Or you may pass in a defined function just like showResults