Question

How can access the results of a

tx.executeSql('select query for a table',[],sucessCB);
function sucessCB(tx, results){  //<--- this results param
    console.log(results.row.item(0).name);
}

I tried something like

function(){
    var tab = [];
    tx.executeSql('select query for a table',[],sucessCB);

    function sucessCB(tx, results){  //<--- this results param
        console.log(results.row.item(0).name);
        for(i=0;i<results.length;i++){
            tab.push(results.row.item(i))
        }
    }

    console.log(tab);  //<--- this returns always null
}

how can access the variable outside the callback function or is there a way to store a sql results in variable directly. Is there a way to send variable into a callback function again in the

tx.executeSql('another select query',[],function(tx, results, tab ){  // <-- this inside sucessCB
console.log(tab);
});

In all the scenario the variable is null. Is there a another way to do this. Any suggestion would be helpful thanks.

Answer 1

You use callback as follow:

var querySql = function(sql, callback) {

  tx.executeSql(sql,[],sucessCB);

  function sucessCB(tx, results){  //<--- this results param
    var tab = [];
    for(i=0;i<results.length;i++){
        tab.push(results.row.item(i))
    }
    callback(tab);
  }
}

querySql('select query for a table', function(result) {
   console.log(result); 
}

However this kind of problem is better solved by using Deferred concept.

var querySql = function(sql) {
  var df = $.Deferred();
  tx.executeSql(sql,[],sucessCB, errCB);

  function sucessCB(tx, results){  //<--- this results param
    var tab = [];
    for(i=0;i<results.length;i++){
        tab.push(results.row.item(i))
    }
    df.resolve(tab);
  }
  function errCB(tx, e) {
    df.reject(e);
  }
}

querySql('select query for a table').done(function(result) {
   console.log(result); 
}