can't get the results of select query in an array with javascript

Question

I have a problem when trying to store the results of a select query into an array with java script . the problem is that inside the function the array is containing the right values but outside it's empty , even when i used a global var it's still empty !!!

db.transaction(function (transaction) {
    var sql = "SELECT * FROM Question where idEnq=" + idEn;

    transaction.executeSql(sql, undefined, function (transaction, result) {
        var res = document.getElementById('results');
        res.innerHTML = "<ul>";
        if (result.rows.length) {
            for (var i = 0; i < result.rows.length; i++) {
                var row = result.rows.item(i);
                ch[i] = new qu(row.id, row.text, row.type);
                res.innerHTML += '<li>' + row.id + '&nbsp;' + ch[i].text + '&nbsp;' + ch[i].type + '</li>';
            }
            tablo = ch;
        } else {
            alert("No choices");
            res.innerHTML += "<li> No choices </li>";
        }

        res.innerHTML += "</ul>";
    }, onError);
}); // here the ch and the tablo array are empty

Don't put idEn directly in the query text, that is what bind variables (the second argument for executeSql) is for. — user1233508
– user1233508, Commented May 6, 2012 at 16:31

ThiefMaster · Accepted Answer · 2012-05-06 16:29:22Z

4

You are using asynchronous functions. Anything that wants to use the data "returned" by those functions need to be in the callback. Of course you can assign this data e.g. to a global variable, but that variable will only have the value after the callback has run (asynchronously).

answered May 6, 2012 at 16:29

ThiefMaster

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4 Comments

MarwaInsat Over a year ago

sorry but I'm new to JS and I don't know how to use the callback !!

ThiefMaster Over a year ago

Move your code that is currently after the db.transaction(...) call inside the callback, i.e. after res.innerHTML += "</ul>";

MarwaInsat Over a year ago

this code is already inserted into a function that returns the array , do i have to add the callback parameter as follow : function GetQuest(idEn,callback) {...... ............... return tablo;} and then what ?

MarwaInsat Over a year ago

I followed the answer given here stackoverflow.com/questions/9933877/… but an error occurs saying 'Uncaught ReferenceError: callback is not defined' so what should I do ??

Amira Manai · Accepted Answer · 2012-05-06 16:37:54Z

0

you're new so have look here http://pietschsoft.com/post/2008/02/JavaScript-Function-Tips-and-Tricks.aspx there's a part talking about calling JavaScript Function asynchronously

answered May 6, 2012 at 16:37

Amira Manai

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