Atmosphere/atmosphere — comment on commit c47d2e6e6512d487d3bd67657e35518b90eb1e4e
File: modules/jquery/src/main/webapp/jquery/jquery.atmosphere.js line 167
By flowersinthesand:

IE6 and 7 don't support native JSON.

While implementing JSON.parse is pretty easy as you can see jQuery.parseJSON, implementing JSON.stringify is somewhat tiresome. You may need Crockford's json2.js to use JSON.stringify. https://github.com/douglascrockford/JSON-js