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javascript set a variable if undefined
... x === 'undefined') ? your_default_value : x;
On newer browsers it's actually safe to write:
var x = (x === undefined) ? your_default_value : x;
but be aware that it is possible to subvert this on older browsers where it was permitted to declare a variable named undefined that has a defined val...
Can scripts be inserted with innerHTML?
... that you've inserted as DOM text.
MooTools will do this for you automatically, and I'm sure jQuery would as well (depending on the version. jQuery version 1.6+ uses eval). This saves a lot of hassle of parsing out <script> tags and escaping your content, as well as a bunch of other "gotchas...
How do I parse command line arguments in Bash?
Say, I have a script that gets called with this line:
37 Answers
37
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Python to print out status bar and percentage
...
There's a Python module that you can get from PyPI called progressbar that implements such functionality. If you don't mind adding a dependency, it's a good solution. Otherwise, go with one of the other answers.
A simple example of how to use it:
import progressbar
from time...
How to select first and last TD in a row?
...d:first-child,
tr td:last-child {
/* styles */
}
This should work in all major browsers, but IE7 has some problems when elements are added dynamically (and it won't work in IE6).
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compareTo() vs. equals()
...ls() because to me this seems to be the most natural method for it. After all, its name already says what it is intended to do. However, a colleague of mine recently told me had been taught to use compareTo() == 0 instead of equals() . This feels unnatural (as compareTo() is meant to provide a...
Observer Design Pattern vs “Listeners”
It seems to me that the Observer design pattern as described in GOF is really the same thing as Listeners found in various toolkits. Is there a difference between the concepts, or are Listeners and Observers really the same thing.
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Rails: convert UTC DateTime to another time zone
...e names of the ActiveSupport time zones by doing:
ActiveSupport::TimeZone.all.map(&:name)
# or for just US
ActiveSupport::TimeZone.us_zones.map(&:name)
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Difference between UTF-8 and UTF-16?
...c. occupy one byte which is identical to US-ASCII representation. This way all US-ASCII strings become valid UTF-8, which provides decent backwards compatibility in many cases.
No null bytes, which allows to use null-terminated strings, this introduces a great deal of backwards compatibility too.
UT...
How do you discover model attributes in Rails?
... am finding it difficult to easily see what attributes/properties exist on all of my model classes since they are not explicitly defined in my class files.
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