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Appending a line to a file only if it does not already exist
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This actually doesn't work when the line starts with a -.
– hyperknot
Feb 6 '18 at 22:03
1
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How to change CSS using jQuery?
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@Ender: using css() all the css is reset and only the css mentioned in this function persists. How can I only add css which is to be changed and retain previous css ?
– SimpleGuy
Sep 2 at 5:46
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Check if an element contains a class in JavaScript?
...List .contains method:
element.classList.contains(class);
This works on all current browsers and there are polyfills to support older browsers too.
Alternatively, if you work with older browsers and don't want to use polyfills to fix them, using indexOf is correct, but you have to tweak it a ...
Is it feasible to compile Python to machine code?
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There are several options:
Use Psyco, which emits machine code dynamically. You should choose carefully which methods/functions to convert, though.
Use Cython, which is a Python-like language that is compiled into a Python C extension
Use PyPy, which has a translator from RPython (a restricted ...
How to delete multiple files at once in Bash on Linux?
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Bash supports all sorts of wildcards and expansions.
Your exact case would be handled by brace expansion, like so:
$ rm -rf abc.log.2012-03-{14,27,28}
The above would expand to a single command with all three arguments, and be equivale...
What is the difference between JOIN and UNION?
...ed when columns from one table match columns from another. This match is called the join condition.
This makes joins really great for looking up values and including them in results. This is usually the result of denormalizing (reversing normalization) and involves using the foreign key in one ta...
C++, What does the colon after a constructor mean? [duplicate]
...e the demo class is being constructed. For instance:
class Demo{
int foo;
public:
Demo(){ foo = 1;}
};
Would first place a value in foo before setting it to 1. It's slightly faster and more efficient.
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Rails “validates_uniqueness_of” Case Sensitivity
... 3rd Edition:
...despite its name, validates_uniqueness_of doesn’t really guarantee that column values will be unique. All it can do is verify that no column has the same value as that in the record being validated at the time the validation is performed. It’s possible for two records to be ...
Ways to circumvent the same-origin policy
... set document.domain to othercompany.com.
With this method, you would be allowed to exectue javascript from an iframe sourced on a subdomain on a page sourced on the main domain. This method is not suited for cross-domain resources as browsers like Firefox will not allow you to change the document...
How to pass optional arguments to a method in C++?
... do_something();
else
do_something_else();
}
you can call myfunc in both ways and both are valid
myfunc(10); // Mode will be set to default 0
myfunc(10, 1); // Mode will be set to 1
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