An array is undefined in javascript

Question

I am actually trying to retrieve something for a sqlite database and store the results in an array. So I create an array and pass it as an argument to the function. Then after the function returns, the array remains undefined. What is the problem with that?

function initGraphView()
{
   var resultsArray=new Array(12);
   getGraphData(defaultQueryString,resultsArray);
   alert(resultsArray[0]); //undefined
}

    getGraphData=function(queryString,resultsArray)
{
dbConnection.transaction(function(tx){
 tx.executeSql(queryString, [],
    function(SQLTransaction, data)
    {
        for(var i=0;i

please post your full getGraphData function and also usually arrays are initialized like var resultsArray = []; — errorhandler
– errorhandler, Commented Apr 2, 2011 at 4:50

InfinitiesLoop · Accepted Answer · 2011-04-02 04:51:15Z

1

I don't really know what the getGraphData function is doing, but it looks like it's asynchronous. See the function passed into dbConnection.transaction? That's probably a callback that executes once the operation is complete, at some later time. You will need to handle the result from there instead.

Also, the function is passed the array as parameter 'anArray', but you're not using that parameter, you're using 'resultsArray'. Since that isn't defined in that scope, it's not the same array you think.

answered Apr 2, 2011 at 4:51

InfinitiesLoop

14.7k3 gold badges33 silver badges34 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Tony Kennah · Accepted Answer · 2011-04-02 04:56:12Z

1

I don't know javascript well but there is something called passByValue and PassByReference... maybe try setting what you return, something like:

    vatAdded=addVAT(orderTotal)

    function addVAT(value){
      var newValue
      newValue=value*1.07
      return newValue
    }

HTH

answered Apr 2, 2011 at 4:56

Tony Kennah

3164 silver badges18 bronze badges

Comments

Gaurav · Accepted Answer · 2011-04-02 05:08:56Z

1

you are not assigning the return value of function getGraphData to any variable.

resultsArray = getGraphData(defaultQueryString,resultsArray);

function initGraphView()
{
   var resultsArray=new Array(12);
   resultsArray= getGraphData(defaultQueryString,resultsArray);
   alert(resultsArray[0]); // undefined.
}




getGraphData=function(queryString,anArray)
{
dbConnection.transaction(function(tx){
 tx.executeSql(queryString, [],
    function(SQLTransaction, data)
    {
      for(var i=0;i<data.rows.length;i++)
      {
        var row = data.rows.item(i);
        var aName = row[name];
        var aMonth=row[month];
        var total=row[totalAmount];
        var aCategoryName=row[categoryName];
        anArray[parseInt(aMonth)]=parseFloat(total);
      }
    }
  )
});

return anArray;  // use return statement here
}

edited Apr 2, 2011 at 5:08

answered Apr 2, 2011 at 4:51

Gaurav

28.8k9 gold badges54 silver badges81 bronze badges

2 Comments

chaitanya Over a year ago

tried this out, it doesn't work. I guess its because of the asynchronous behavior in which the request is processed.

chaitanya Over a year ago

ur answer is right in the normal situation, but since i was using this script to fetch a data from a database, the call to it was asynchronous and thus the array came out to be undefined.

typo.pl · Accepted Answer · 2011-04-02 04:52:52Z

0

resultsArray from initGraphView is not visible in the getGraphData function object.

You need to change anArray to resultsArray.

answered Apr 2, 2011 at 4:52

typo.pl

8,9302 gold badges30 silver badges29 bronze badges

Collectives™ on Stack Overflow

An array is undefined in javascript

4 Answers 4

Comments

Comments

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related