javascript - Cancelling an event being delayed -


this question has answer here:

disclaimer : i'm not super proficient in javascript , there's small js code part in .net program.

i have 2 dropdown lists, reportlist , yearlist. first one's selected value dynamically populates second dropdown list using ajax. problem is, each time reportlist selected makes query database. there can @ least 200 entries in reportlist , when user uses mousewheel on dropdownlist, application, is, makes hundreds of query in short amount of time , crashes database. far have this

             $('#reportlist').change(function () {              settimeout(function () { populateyearsdropdownlist() }, 2000);          });

i've played stoppropagation() , didn't work. can't test efficiently since test db hosted , maintained else.

i'd able scroll through without prompting queries amount of reports have gone through. thinking of adding small delay, each function ".change" cancelling last function call.

i think wasn't thought through beginning, want fix in small amount of time have.

i'd suggest assigning settimeout variable (with proper scope accessibility) , using cleartimeout stop timeout.

to read more settimeout , cleartimeout.

an example like:

var mytimeout; $('#reportlist').change(function () {     if (mytimeout) cleartimeout(mytimeout);     mytimeout = settimeout(function () { populateyearsdropdownlist() }, 2000); });

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