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How to check for an undefined or null variable in JavaScript?
...the most efficient to test for 'null or undefined' (which is the questions topic). It is by no means uncommon (used 43 times in jQuery 1.9.1), since very often you know that the variable was declared - or you test for an property of an existing object like if( o.foo == null).
–...
How to add items to a spinner in Android?
.../spinner"
android:layout_width="fill_parent"
android:drawSelectorOnTop="true"
android:prompt="@string/spin"
android:entries="@array/spinnerItems"
/>
Items definition in the file array.xml:
<resources>
<string-array name="spinnerItems">
<item>item1&...
Makefiles with source files in different directories
...nother subdirectory, you are probably better off with a single makefile at top-level.
See Recursive Make Considered Harmful for the full rationale, but basically you want make to have the full information it needs to decide whether or not a file needs to be rebuilt, and it won't have that if you on...
How to launch html using Chrome at “--allow-file-access-from-files” mode?
...2.168.88.1:8080
http:192.168.0.7:8080
http:127.0.0.1:8080
Hit CTRL-C to stop the server
Or as prusswan suggested, you can also install Python under windows, and follow the instructions below.
--- For Linux ---
Since Python is usually available in most linux distributions, just run python -m S...
In Python, what is the difference between “.append()” and “+= []”?
... 0 ('spam')
15 CALL_FUNCTION 1
18 POP_TOP
19 LOAD_CONST 1 (None)
22 RETURN_VALUE
>>> dis.dis(compile("s = []; s += ['spam']", '', 'exec'))
1 0 BUILD_LIST 0
3 STORE_NAME ...
How do I know if a generator is empty from the start?
...:
def peek(iterable):
try:
first = next(iterable)
except StopIteration:
return None
return first, itertools.chain([first], iterable)
Usage:
res = peek(mysequence)
if res is None:
# sequence is empty. Do stuff.
else:
first, mysequence = res
# Do something ...
MYSQL OR vs IN performance
...y given question.
This might be of some help: http://forge.mysql.com/wiki/Top10SQLPerformanceTips
Regards,
Frank
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psql: FATAL: Peer authentication failed for user “dev”
...ortant note:
Definition order in pg_hba.conf matters - rules are read from top to bottom, like iptables, so you probably want to add proposed rules above the rule:
host all all 127.0.0.1/32 ident
...
Text Progress Bar in the Console [closed]
...2
To use the above functions in Python 2, set the encoding to UTF-8 at the top of your script:
# -*- coding: utf-8 -*-
And replace the Python 3 string formatting in this line:
print(f'\r{prefix} |{bar}| {percent}% {suffix}', end = printEnd)
With Python 2 string formatting:
print('\r%s |%s| %s%% %s...
How to make a function wait until a callback has been called using node.js
...bers, (3) Use promises, for example the Q-library, (4) Use a thin layer on top of javascript, that looks blocking, but compiles to async, like maxtaco.github.com/coffee-script
– Jakob
Mar 21 '13 at 10:52
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