javascript: if{"X" in OBJECT} -- an alternative to {if (OBJECT.X) }

[Darren Dirt]

I was just looking at the forum's HTML source*, and noticed some code that uses this syntax.

Basically it seems to be a surprising way of using the same elements that come into play with the more common {for (KEY in OBJECT)}

I realize now that it's probably a "safer" way of saying 'does OBJECT contain a property/method/value called "X", if you think "X" might ever have the value of 0 or "".

http://stackoverflow.com/questions/1119336/in-statement-in-javascript-jquery


Maybe I've just been an idiot for a long time, but instead of saying {if("getElementById" in document)...} I've been using the more common {if(document.getElementById)...} which should always be fine with METHODS.

However, I realize now that if I'm ever doing some kind of a "run only one time" kind of global flag or whatever, then {if(!"firstFlag" in window)} would be far better than {if(!window.firstFlag)} if there was ever the chance of firstFlag being 0 or "" #self-face-palm



PS: using Google to search for the definition/usage of the "in" js function is ... a challenge, shall we say? So here ya go:
https://developer.mozilla.org/en-US/docs/JavaScript/Guide/Expressions_and_Operators#in

(and there's a neat/surprising/useful example using arrays here -- https://developer.mozilla.org/en-US/docs/JavaScript/Guide/Expressions_and_Operators#Deleting_array_elements )







* if you're curious, this was the code that made me go "wuh? is that valid javascript?"
if ('XMLHttpRequest' in window)
{
...
}

[Mr. Analog]

You may like this actually, http://www.youtube.com/watch?v=taaEzHI9xyY

Some goodies in there that will make you think.

I'm not a big fan of Douglas Crockford, I think he's an arrogant jerk, but he does make some valid (and entertaining) points on usage (of which looping is but one)

[Thorin]

Nice finds.

I miss writing code, been debugging single-customer-single-environment-that-I-can't-access-directly bugs for a while now.

[Mr. Analog]

Well that sucks, you must be good at fixing bugs though they keep giving them to you! (I'M KIDDING!!)

[Darren Dirt]

Well that sucks, you must be good at fixing bugs though they keep giving them to you!

[Mr. Analog]

Hah, so true.

And all cool design projects eventually morph into support projects (unless you are a contractor lol)

[Darren Dirt]

Hah, so true.

And all cool design projects eventually morph into support projects (unless you are a contractor lol)

A smart developer is not just good at coding, but at coding INTENTIONALLY BADLY (i.e. sub-par enough that bugs will occasionally but consistently crop up, slowly and over a long period of time, but well enough that the app basically works) ( )

[Mr. Analog]

Like, what drug exactly do they put in the water there LOL

I enjoy doing things right even if I have to tear down half of what's there, I no longer have that fear, because I have lived with the consequences of 8 billion layered bandaids.

NEVER AGAIN

[Thorin]

source: http://dilbert.com/strips/comic/1995-11-13/

-----

With the amount of development work always outstripping the number of available developers, I'd say a smart developer writes the best possible code so they can get paid to work on new projects instead of having to stick to old projects and old technology.

[Mr. Analog]

I hear ya, we have a guy on our team who through no fault of his own (well, let's call it attrition maybe) is now unhappily married to a codebase he doesn't want to maintain.

[Thorin]

In the famous words of every developer everywhere, ever: we need to rewrite this app from scratch.

[Mr. Analog]

LOL