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How to check a not-defined variable in JavaScript
...ue for things that don't exist, undefined. The DOM returns null for almost all cases where it fails to find some structure in the document, but in JavaScript itself undefined is the value used.
Second, no, there is not a direct equivalent. If you really want to check for specifically for null, do:
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How can I open a cmd window in a specific location?
... can I open a cmd window in a specific location without having to navigate all the way to the directory I want?
40 Answers
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What is the largest TCP/IP network port number allowable for IPv4?
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@JessieArr in both those cases it's not really a 65536 issue, it's an issue of A)programs not releasing connections, leaving them in a "WAIT" state that netstat shows combined with B)some earlier windows versions only going from 1024-5000 for dynamic ports.And even t...
Operator overloading in Java
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You are saying we cant create wrapper in java? Such as SmallInteger like Integer?
– huseyin tugrul buyukisik
Sep 12 '12 at 10:58
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Switch on Enum in Java [duplicate]
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You actually can switch on enums, but you can't switch on Strings until Java 7. You might consider using polymorphic method dispatch with Java enums rather than an explicit switch. Note that enums are objects in Java, not just symbol...
git update-index --assume-unchanged returns “fatal unable to mark file”
...nd downloaded the latest version of git, but this did not help.
What I finally realized is that this command is case sensitive! This includes the full path and file name. After updating path to the directory so that the full path was specified with proper casing, the command executed properly.
N...
Removing non-repository files with git?
...es. By default, it will only print what it would have removed, without actually removing them.
Given the -f flag to remove the files, and the -d flag to remove empty directories as well :
git clean -df
Also removing ignored files :
git clean -dfx
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Javascript - Track mouse position
I am hoping to track the position of the mouse cursor, periodically every t mseconds. So essentially, when a page loads - this tracker should start and for (say) every 100 ms, I should get the new value of posX and posY and print it out in the form.
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Signed versus Unsigned Integers
...at text but I found another link. Go to the 9th page of the PDF (it is actually the 38th page of the book) and you can see the section called Data Representation (Section 1.3). It has the explanation of all the things said above. lms.uop.edu.jo/lms/pluginfile.php/2420/mod_resource/content/1/…
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Expert R users, what's in your .Rprofile? [closed]
... Yes, the local({ ... }) as shown in help(Startup) is what I usually do these days in Rprofile.site. Haven't needed the X11 hack in a while :)
– Dirk Eddelbuettel
Aug 27 '15 at 11:02
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