Show WalkScore (GreaseMonkey hack) - Website Questions

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Show WalkScore (GreaseMonkey hack)

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rouftop
Visitor
Posts: 3
Registered: 01-25-2008

Message 1 of 4

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Hey,
My wife and I are trying to find places in particularly walkable neighborhoods. To that end, I just whipped up this little GreaseMonkey script. It adds a "Show Walkability" link underneath the address on the "listing details" page. That link will pop the address into Walk Score in a new window, so you can see how far you have to go to find the nearest coffeeshop, bar, grocery store, etc.

http://userscripts.org/scripts/show/21365

Happy house hunting,
rouftop

Kudos!

01-25-2008 01:29 PM

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Re: Show WalkScore (GreaseMonkey hack)

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dub
Contributor
Posts: 22
Registered: 03-24-2008

Message 2 of 4

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Awesome script!
Would it be possible to link to yelp?

Target URL:
http://www.yelp.com/maptastic?lon=-71.17848&lat=42.37185&zoom=12

I see the lat/long in here

var g_listing = {
latitude: 42.403088,
longitude: -71.243636,
icon: "<div class='homePushpin'><img class='ico_map_for_sale' src='http://p1.rfimg.us/v4.5.3/images/clear.gif'/></div>"
};

But this fails silently after 'in showYelp'..any idea how to get it to work?

function showYelp() {

alert('in showYelp');
alert('Latitude='+ g_listing.latitude);
var loc = "http://www.yelp.com/maptastic?lon=" +g_listing.longitude+ "&lat=" +g_listing.latitude +"&zoom=14";

var div = document.createElement('div');
var anc = document.createElement('a');
anc.target = '_new';
anc.href = loc;
anc.innerHTML = "Show Walkability";
div.appendChild(anc);
var sibling = document.getElementById('address_line_2');
sibling.parentNode.insertBefore(div, sibling.nextSibling);
}

showYelp();

Kudos!

04-14-2008 09:23 PM

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Re: Show WalkScore (GreaseMonkey hack) [ Edited ]

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Navtej
Redfin Staff
Posts: 3
Registered: 04-15-2008

Message 3 of 4

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Hi dub,

The reason your script is failing after the first alert is because Greasemonkey cannot access g_listing. Greasemonkey scripts don't actually run directly in the context of the page, but work inside a sandbox for security reasons. This O'Reilly article details some of the caveats pretty well.

That said, you can make your script work by referring to unsafeWindow.g_listing instead of just g_listing. unsafeWindow is the actual window object rather than Greasemonkey's proxy, so it contains the custom fields added by the page's script. Just take note (from the O'Reilly article):

It's called unsafeWindow for a reason: its properties and methods could be redefined by the page to do virtually anything. You should never call methods on unsafeWindow unless you completely trust the remote page not to mess with you. You should only ever use it as a parameter to call functions defined by the original page, or to watch window properties...

Also note, that you can actually see the error messages in Firefox's error console (under the Tools menu) rather than just relying on window.alert().

Message Edited by Navtej on 04-15-2008 12:59 PM

Navtej Sadhal
Software Developer - Search Team

Kudos!

04-15-2008 11:15 AM