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How to wrap async function calls into a sync function in Node.js or Javascript?
...pose you maintain a library that exposes a function getData . Your users call it to get actual data:
var output = getData();
Under the hood data is saved in a file so you implemented getData using Node.js built-in fs.readFileSync . It's obvious both getData and fs.readFileSync are sync ...
event.preventDefault() vs. return false
...eturn false from within a jQuery event handler is effectively the same as calling both e.preventDefault and e.stopPropagation on the passed jQuery.Event object.
e.preventDefault() will prevent the default event from occuring, e.stopPropagation() will prevent the event from bubbling up and return f...
ORA-00979 not a group by expression
...
You must put all columns of the SELECT in the GROUP BY or use functions on them which compress the results to a single value (like MIN, MAX or SUM).
A simple example to understand why this happens: Imagine you have a database like this:
...
How does a Java HashMap handle different objects with the same hash code?
...ng bucket, and then it will compare the key that you gave with the keys of all pairs in the bucket, by comparing them with equals().
Now you can see how this is very efficient for looking up key-value pairs in a map: by the hash code of the key the hashmap immediately knows in which bucket to look,...
What is meant by “managed” vs “unmanaged” resources in .NET?
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The term "unmanaged resource" is usually used to describe something not directly under the control of the garbage collector. For example, if you open a connection to a database server this will use resources on the server (for maintaining the connection) and po...
What does 'public static void' mean in Java?
...ely different things:
public means that the method is visible and can be called from other objects of other types. Other alternatives are private, protected, package and package-private. See here for more details.
static means that the method is associated with the class, not a specific instance (...
How do I install ASP.NET MVC 5 in Visual Studio 2012?
Is there a way to install ASP.NET MVC 5 in Visual Studio 2012?
11 Answers
11
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MySQL 'create schema' and 'create database' - Is there any difference
... CREATE SCHEMA is a synonym for CREATE DATABASE as of MySQL 5.0.2.
this all goes back to an ANSI standard for SQL in the mid-80s.
That standard had a "CREATE SCHEMA" command, and it served to introduce
multiple name spaces for table and view names. All tables and views were
created within a "s...
How to install psycopg2 with “pip” on Python?
I'm using virtualenv and I need to install "psycopg2".
33 Answers
33
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How do I write a for loop in bash
... doSomething($n)
done
Note the $(...) syntax. It's a bash behaviour, it allows you to pass the output from one command (in our case from seq) to another (the for)
This is really useful when you have to iterate over all directories in some path, for example:
for d in $(find $somepath -type d)
do...