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How can I check for “undefined” in JavaScript? [duplicate]
...n window; // true
"theFoo" in window; // false
If you are interested in knowing whether the variable hasn't been declared or has the value undefined, then use the typeof operator, which is guaranteed to return a string:
if (typeof myVar !== 'undefined')
Direct comparisons against undefined are ...
How does JavaScript .prototype work?
... really got my head around this prototype-based programming, does any one know how this works?
26 Answers
...
What breaking changes are introduced in C++11?
I know that at least one of the changes in C++11 that will cause some old code to stop compiling: the introduction of explicit operator bool() in the standard library, replacing old instances of operator void*() . Granted, the code that this will break is probably code that should not have been v...
Code for a simple JavaScript countdown timer?
... Date().getTime();
var interval = setInterval(function() {
var now = time-(new Date().getTime()-start);
if( now <= 0) {
clearInterval(interval);
complete();
}
else update(Math.floor(now/1000));
},100); // the smaller this number, the...
JSON datetime between Python and JavaScript
...ime.datetime, datetime.date))
else None
)
json.dumps(datetime.datetime.now(), default=date_handler)
'"2010-04-20T20:08:21.634121"'
Which is ISO 8601 format.
A more comprehensive default handler function:
def handler(obj):
if hasattr(obj, 'isoformat'):
return obj.isoformat()
...
When to use single quotes, double quotes, and backticks in MySQL
...write queries. I also understand the importance of being consistent. Until now, I have randomly used single quotes, double quotes, and backticks without any real thought.
...
Build unsigned APK file with Android Studio
I'm developing an android app with the Android Developer Tool.
Now I tried the new Android Studio, everything works fine if connect my smartphone with the pc and directly run the program in the Android Studio.
But now I want to test the program with other smartphones without connecting them to my pc...
Adding days to a date in Python
...ng it is a dumb idea? What is datetime? You can't rely on convention to know, but always have to look at the imports.
– Xiong Chiamiov
Jun 5 '17 at 17:47
10
...
Which parts of Real World Haskell are now obsolete or considered bad practice?
In the chapter 19 of Real World Haskell a lot of the examples now fail due to the change of Control.Exception .
1 Answer...
What is the best IDE to develop Android apps in? [closed]
...S
Android Studio has officially come out of beta and been released. It is now the official IDE for Android Development - Eclipse won't be supported anymore. It is definitely the IDE of choice for Android Development. Link to download page: http://developer.android.com/sdk/index.html
NEWS
As of ...