Node.js Checkbox Iteration

How do I iterate through the checked checkboxes, without hard coding and checking each box one at a time. Kinda like this link, but with Node.js and not JavaScript Iterate all checkbox in JavaScript:

So I'm attempting to display the contents of my database (using MySQL), but I don't want to hard code 'req.body.checkboxName' for every checkbox in case a new column is added onto a table (the checkboxes are each of the columns in a given table). So I need to find a way that will iterate through every checkbox in the webpage and see if it is checked. If it is then we'll add them together in a string and query for those columns. My code below is for the Node.js POST method (after hitting submit once the checkboxes are checked) and the other is my Pug/Jade code (the JavaScript Templating Engine that I use, sorry it isn't plain html).

In case you're confused how the Pug/Jade file runs initially, another GET method renders that Pug/Jade file with the column names; that GET method is basically the POST method below up until the '//Need help' line

Node.js

app.post('/GetTables', function(req, res){
    var columnsRequest =  'DESCRIBE ' + tableName;
    var columnsList = [];
    connection.query(columnsRequest, function(err, results, fields) {
        if(err){
             throw err;
        }
        for (var index in results) {
            console.log(results[index].Field);
            columnsList.push(results[index].Field);
        }
    });


    //Need help, the next 5 or so lines are non-working ~psuedocode
    var checkedList = '';    
    req.body.CHECKBOXES.each(function(index, element){
        if(CHECKBOX.ischecked(){
            checkedList += CHECKBOX.name() + ', '
        }
    });


    var mysqlRequest =  'SELECT ' + checkedList + ' FROM ' + tableName;
    connection.query(mysqlRequest, function(err, results, fields) {
        if(err){
            throw err;
        }
        res.render('webPage', {'columnstodisplay': results});
    });

});

Pug/Jade

form(method = 'POST', action = '/GetTables', id = 'tableform')
    fieldset
        each item in columns
            //this loop sets up the checkboxes for each of the columns
            p
                input(type="checkbox", name=item, value=item)
                span #{item}
                br
        input(type ='submit', value ='Submit')

Thanks in advance!