Function inside for loop getting "i" variable undefined in sqlite executesql Query javascript

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Javascript closure inside loops - simple practical example

I am using webservice to get the data in the form of JSON by using javascript and want to store that data in Sqlite Database. here i used for loop to store data one by one in Database by executeSql Query. But problem is function inside the for loop getting "i" value out of scope means showing undefined. I am trying to solve this problem by last 5 days. Any suggestion ?

Thanks

function GetGeoValues() {
    $.get("http://example.in/projects/api.php?usn=user&pwd=****&var=something", function (Jdata) {
        var geoid = new Array();
        var geoname = new Array();
        var i;
        for (i = 0; i < Jdata.vact_geography.length; i++) {
            geoid.push(Jdata.vact_geography[i].geo_id);
            geoname.push(Jdata.vact_geography[i].geo_name);
            db.transaction(function (transaction) {
                alert(geoid[i]); // here i showing undefined
                transaction.executeSql('INSERT INTO vact_geography VALUES(' + parseInt(geoid[i]) + ',"' + geoname[i] + '")');
            });
        }
    });
}

@ Felix Kling ... Thanks Alot..U just save my next 5 days.. solved in 10 min...Thank You Once again — Manzur Husain, Sep 19 '11 at 10:59

score 0 · Answer 1 · answered Sep 19 '11 at 10:18

0

Here inner function and outer function concept is considered. So the outer function have the var i. But in inner function i is not defined. Thats y its throwing error as "undefined"

answered Sep 19 '11 at 10:18

Nagarajan

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That is incorrect. The inner function is a closure and has access to all variables defined in higher scopes. The problem is that upon invocation of the function, the value of `i` is not a valid index in the array. – Felix Kling Sep 19 '11 at 10:27

score 0 · Accepted Answer · answered Sep 19 '11 at 10:52

I'm not sure, but this can happen, if function(transaction) executed in asynchronous mode. In this case variable i after for loop is finished must be equals to Jdata.vact_geography.length, and, as result geoid[i] equals to undefined. To workarround this try next:

function GetGeoValues() {
  $.get("http://example.in/projects/api.php?usn=user&pwd=****&var=something",
         function(Jdata) {
           var geoid=new Array();
           var geoname=new Array();
           for(var i=0;i<Jdata.vact_geography.length;i++) {
             geoid.push(Jdata.vact_geography[i].geo_id);
             geoname.push(Jdata.vact_geography[i].geo_name);
           }
           db.transaction(function(transaction) {
             for(var i=0;i<geoid.length;i++) {
               alert(geoid[i]); // here i showing undefined
               transaction.executeSql('INSERT INTO vact_geography VALUES('+parseInt(geoid[i])+',"'+geoname[i]+'")');
               // All INSERT's executed in one transaction
             }
           });  
         }
       ); 
}

can u please help me how to write SELECT query inside FOR loop using javascript in phonegap app — nida, Oct 08 '13 at 10:14

Function inside for loop getting "i" variable undefined in sqlite executesql Query javascript

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