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Squashing JavaScript Bugs, Grassroots Mapping, GeoJSON and KML


A JavaScript console is an extension that throws a red flag if the JavaScript on your page derails, and shows you where the problem is.
<ndoiron> Firefox, you can do Ctrl+Shift+K.  Less than that,
<seanhorgan> in the world of javascript programming/debugging, firebug is an essential tool to get very familiar with it
<seanhorgan> if you click on the little bug symbol on the bottom right of your firefox window, it should split the screen with the bottom half showing the firebug console
<ndoiron> click the Script tab, then the down arrow, to set JavaScript to Enabled
<seanhorgan> Google Chrome has a developer mode (ctrl-shift-j, or ctrl-option-j on Apple) that is similar

Grassroots Mapping : Who, What, When, Where, Why?

<ndoiron> went to open source conference at State Dept... they are quite interested in mapping
<DoRight> Get more resources for us?
<ndoiron> got to meet some of the people behind -- they go beyond satellite maps by flying balloons
<introvert> why?
<ndoiron> higher-resolution, more recent, and can be open-sourced
<ndoiron> they took great photos during the BP Oil Spill and now some of those are in Google Maps
<introvert> how old are the satellite images
<ndoiron> introvert: if you have Google Earth you can find exactly how old their images are... it can be a few years
<rrosso> huh, that's cool. do they use GPS hand-held devices, or rely just on their photographs?
<ndoiron> rrosso: they put thousands of photos online, and people vote on whether they're good quality... I will have to post a link to that
<ndoiron> then they use US gov or Google sat maps to line them up
<ndoiron> and "stitch" them together
<ndoiron> website to vote on photos
<DoRight> Yeah, gorgeous fotos!
<DoRight> But if they use google data, does that keep it from being used in opensource?
<ndoiron> I agree, using Google would make it non-free.  But if they're in the US they can use some USGS satellite maps which are free

Loading Maps through JSON or KML
<seanhorgan> I'm trying to host a page with a map that draws icons based on locations from a file
<seanhorgan> is it best to store the data in a json format?  
<seanhorgan> i don't have a concrete example for you (yet), but I'd like to iterate through an array of points and plot them on the map
<ndoiron> it does have GeoJSON for input.  Try that format or KML, which people can view in Google Earth
<seanhorgan> can OSM handle KML?
Leaflet.js can. More on this later.

Get Icon URLs
<introvert> I have one last q- how do I get the filename for icons?
<ndoiron> I don't know if this works in your browser... right click ( two-finger click on map ) and you should have 'Copy Image URL' or 'Copy Image Location'

Task Discussion