Javascript code too slow in Firefox extension using Storage service

Question

I\'m running the following javascript code in firefox extension

highlightLinks: function(e) {

  var anchors = e.target.getElementsByTagName(\"a\");
  let file =         


        

Answer 1

It'll be faster if you pull the createStatement out of the loop, and reuse it, rebinding the parameters each time. The docs for storage say: "Note: If you need to execute a statement multiple times, caching the result of createStatement will give you a noticeable performance improvement because the SQL query does not need to be parsed each time."

So instead of:

for (var i = 0; i < anchors.length; i++) {
  var statement = conn.createStatement("select * from links where url=?1");
  statement.bindStringParameter(0, anchors[i].href);
  // ... do stuff with results

write:

var statement = conn.createStatement("select * from links where url=?1");
for (var i = 0; i < anchors.length; i++) {
  statement.bindStringParameter(0, anchors[i].href);
  // ... do stuff with results

Edit: Also, if you're using a recent Firefox, you can use their asynchronous API to avoid delaying the UI. Instead of calling executeStep, use executeAsync instead.

statement.executeAsync({
  handleResult: function(aResultSet) {
    // ... do stuff with results
  },

  handleError: function(aError) {
    print("Error: " + aError.message);
  },

  handleCompletion: function(aReason) {
    if (aReason != Components.interfaces.mozIStorageStatementCallback.REASON_FINISHED)
      print("Query canceled or aborted!");
  }
});