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Understanding exactly when a data.table is a reference to (vs a copy of) another data.table
...od does. When wrapped with invisible() or when called within a function or script, the print method isn't called.
All this applies inside functions too; i.e., := and set() do not copy on write, even within functions. If you need to modify a local copy, then call x=copy(x) at the start of the funct...
Python error “ImportError: No module named”
... it by adding PYTHONPATH=/usr/local/lib/python2.7/site-packages to startup scripts.
– Johan Snowgoose
Apr 12 '17 at 20:16
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How to detect the physical connected state of a network cable/connector?
...connected state of an RJ45 connector to its socket. Preferably using BASH scripting only.
14 Answers
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MySQL - UPDATE query based on SELECT Query
...ore the intermediate result. (had to write a similar query for a migration script)
– svvac
Sep 21 '17 at 13:39
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Local Storage vs Cookies
...eds this data — the client or the server?
If it's your client (your JavaScript), then by all means switch. You're wasting bandwidth by sending all the data in each HTTP header.
If it's your server, local storage isn't so useful because you'd have to forward the data along somehow (with Ajax or h...
How to save an image locally using Python whose URL address I already know?
...
I wrote a script that does just this, and it is available on my github for your use.
I utilized BeautifulSoup to allow me to parse any website for images. If you will be doing much web scraping (or intend to use my tool) I suggest yo...
What are “first class” objects?
...wer for more details about classes as objects).
Here is an example of Javascript first class functions:
// f: function that takes a number and returns a number
// deltaX: small positive number
// returns a function that is an approximate derivative of f
function makeDerivative( f, deltaX )
{
v...
Do htmlspecialchars and mysql_real_escape_string keep my PHP code safe from injection?
...< or > to do anything dangerous. Our attack vector could just be javascript:alert(document.cookie)
Now resultant HTML looks like
<img src= "javascript:alert(document.cookie)" />
The attack gets straight through.
It gets worse. Why? because htmlspecialchars (when called this way) on...
How can javascript upload a blob?
... actually don't have to use FormData to send a Blob to the server from JavaScript (and a File is also a Blob).
jQuery example:
var file = $('#fileInput').get(0).files.item(0); // instance of File
$.ajax({
type: 'POST',
url: 'upload.php',
data: file,
contentType: 'application/my-binary-typ...
What is the (function() { } )() construct in JavaScript?
...n is executed right after it's created, not after it is parsed. The entire script block is parsed before any code in it is executed. Also, parsing code doesn't automatically mean that it's executed, if for example the IIFE is inside a function then it won't be executed until the function is called.
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