Question

Im having issues with accessing the value of a variable in NodeJS. Here is some example code and the results I get.

for (var z=0, zMessageCount = Description.length; z<zMessageCount; z++){
    console.log(z);
    if(SomeOtherColumnValue[z] > 9){
        client.query('SELECT * FROM my_table WHERE some_column=' + ColumnValue[z], function (err, results) {
            if(results < 1){
                console.log(z);
            }
        })
    }
}

Here is the issue I am having. In for “for” loop the value of z is going from 0 to 14. However when I try to access it from the client.query function its value is 15. It is not adding 1 to itself for every loop. Is there something I am missing here?

Answer 1

You need to wrap z in a function to provide scope.

for (var z=0, zMessageCount = Description.length; z<zMessageCount; z++){
    console.log(z);
    if(SomeOtherColumnValue[z] > 9){
      zQuery(z);  
    }
}

function zQuery (z) {
  client.query('SELECT * FROM my_table WHERE some_column=' + ColumnValue[z], function (err, results) {
      if(results < 1){
         console.log(z);
      }
   });
}