Running a javascript function based on statechange

问题

Following the answer in this stackoverflow question, I am trying to run the following code. But the myfunction takes only one google visualization event. So Is the following code is valid? Or how to handle multiple statechange google visualization events in a single function?

var categoryPicker1, categoryPicker2;
function drawVisualization() {
  // etc.
  categoryPicker1 = // etc...

  categoryPicker2 = // etc...

  // Register to hear state changes.
  google.visualization.events.addListener(categoryPicker1, 'statechange', myfunction);
  google.visualization.events.addListener(categoryPicker2, 'statechange', myfunction);

  // etc.
}

function myfunction() {
  var whereClauses = [];
if (categorypicker1) {
    whereClauses.push("something1 = '" + document.getElementsByClassName('goog-inline-block goog-menu-button-caption')[0].innerHTML + "'")
}
if (categorypicker2) {
    whereClauses.push("something2 = '" + document.getElementsByClassName('goog-inline-block goog-menu-button-caption')[1].innerHTML + "'")
}
whereClause = whereClauses.join(" AND ");

// do something....
}

回答1:

Not really clear from your question, but I assume you're building the SQL query to your database from the selected items in the CategoryPicker. Despite being an EXTREMELY bad/dangerous thing to do (building SQL client side, and sending it to a server), this should be possible by just grabbing the selectedItems from your CategoryPicker, and joining them with " AND ". Like:

values = categoryPicker1.getState().selectedValues;
values = values.concat(categoryPicker2.getState().selectedValues);
var args = values.map(function(_) { return "'" + _ + "'"; });
console.log(args.join(" AND "));

I wouldn't do this if I were you. I would pass the arguments up to the server, and remap them there (after appropriately filtering them, etc). Again this is very dangerous.

来源：https://stackoverflow.com/questions/17780678/running-a-javascript-function-based-on-statechange