open_safari_dev_tools.js

var Safari = Application('Safari');

var SystemEvents = Application('System Events');
var SafariEvents = SystemEvents.processes['Safari'];

var openDevTools = function(deviceName, appName) {
  var getDevSubMenuItem = function(i) {
    return SafariEvents.menuBars[0]
      .menuBarItems['Develop'].menus['Develop']
      .menuItems[deviceName].menus[deviceName]
      .menuItems[i];
  }
  try {
    console.log("Finding correct menu...");
    var labelIndex = 0;
    while (getDevSubMenuItem(labelIndex).name() != appName) {
      console.log("Skipping " + getDevSubMenuItem(labelIndex).name());
      labelIndex += 1;
    }
    getDevSubMenuItem(labelIndex + 1).click();
    Safari.activate();
    return true;
  } catch (e) {
    return false;
  }
}

var didSucceed = false;
while (!didSucceed) {
  console.log("Attempting to open dev tools");
  delay(1);
  didSucceed = openDevTools("Slam Jamsen's iPhone", "HTML5 Fart App 2.0");
}