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How to check for an undefined or null variable in JavaScript?
...xistingObj.someUndefProperty. An undefined property doesn't yield an error and simply returns undefined, which, when converted to a boolean, evaluates to false. So, if you don't care about
0 and false, using if(obj.undefProp) is ok. There's a common idiom based on this fact:
value = obj.prop || de...
Writing a dict to txt file and reading it back?
...mes not recommended. The problem is that eval() will evaluate any string, and if someone tricked you into running a really tricky string, something bad might happen. In this case, you are just running eval() on your own file, so it should be okay.
But because eval() is useful, someone made an alt...
Hidden features of Windows batch files
What are some of the lesser know, but important and useful features of Windows batch files?
91 Answers
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Moving Files into a Real Folder in Xcode
...sing the browser in Xcode to access everything, stuff was nicely organized and I was happy.
12 Answers
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What is the id( ) function used for?
I read the Python 2 docs and noticed the id() function:
13 Answers
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Delete last commit in bitbucket
I made a mistake and I don't know how to delete my latest push in the repository. I pull the latest updates of the app but it has conflicts and I push it to repository.
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WITH CHECK ADD CONSTRAINT followed by CHECK CONSTRAINT vs. ADD CONSTRAINT
I'm looking at the AdventureWorks sample database for SQL Server 2008, and I see in their creation scripts that they tend to use the following:
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Is there a way to 'uniq' by column?
...eed the ,1 in -k1,1? why not just -k1?
– hello_there_andy
Nov 24 '14 at 20:10
19
@hello_there_and...
JavaScript pattern for multiple constructors
...ors.
If you want a function to behave differently depending on the number and types of parameters you pass to it, you'll have to sniff them manually. JavaScript will happily call a function with more or fewer than the declared number of arguments.
function foo(a, b) {
if (b===undefined) // par...
Android Studio - local path doesn't exist
After updating Android Studio to 0.2.4 I can't get my project to deploy. There is a complete mismatch of the apk filename.
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