Tuesday, November 18, 2008

Notes from the (Javascript) Noob: conditionally enable console debugging

Today I ran into a problem when the primary user of my monitoring app wanted to know why graphs werent rendering for him. I checked the site from my machine and all looked good. I checked the site from another devs machine, and again, everything was rendering. At this point I was confused.

I knew it had to be something in the javascript rendering, so I had the user install firebug. Instead of a JS error (or 10), the page loaded fine. Hmmm. I then wanted to see if the requests I was firing from the page to the Google Charts API were actually going through. We tabbed to the FB net tab, which was disabled. When I had him enable that, plus the console, the graphs rendered.

Doh! I was using console.log to check a value, and forgot that not everyone in the known universe runs with FB enabled. In order to continue to log, I've done this:

function log(str) {
var c = window.console; if (c) {

I'm kind of surprised that (a) I wasn't getting a 'console object not defined' in the naive install of FB (which evaluated JS, but had console/net logging turned off), and that (b) if console was present as implied by (a), that logging would degrade gracefully. But the code above works, and I'll take that over sheer speculation.

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