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Detecting an “invalid date” Date instance in JavaScript
...
Here's how I would do it:
if (Object.prototype.toString.call(d) === "[object Date]") {
// it is a date
if (isNaN(d.getTime())) { // d.valueOf() could also work
// date is not valid
} else {
// date is valid
}
} else {
// not a date
}
Update [2018-05-31]: If you...
JavaScript OR (||) variable assignment explanation
...otcha' which is that the last one will always get assigned even if they're all undefined, null or false. Setting something you know isn't false, null, or undefined at the end of the chain is a good way to signal nothing was found.
– Erik Reppen
Aug 29 '11 at 1...
Count, size, length…too many choices in Ruby?
...1
In the case where you don't provide a parameter to count it has basically the same effect as calling length. There can be a performance difference though.
We can see from the source code for Array that they do almost exactly the same thing. Here is the C code for the implementation of array.l...
How to use regex with find command?
.... For example 81397018-b84a-11e0-9d2a-001b77dc0bed.jpg. I want to find out all these images using "find" command:
7 Answers...
Create new tmux session from inside a tmux session
... Thanks for the very complete answer, this answered a few of my questions all at once!
– mdekkers
Jun 1 '18 at 4:33
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Is it faster to count down than it is to count up?
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Is it really true? and if so does anyone know why?
In ancient days, when computers were still chipped out of fused silica by hand, when 8-bit microcontrollers roamed the Earth, and when your teacher was young (or your teacher's tea...
Begin, Rescue and Ensure in Ruby?
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Yes, ensure ensures that the code is always evaluated. That's why it's called ensure. So, it is equivalent to Java's and C#'s finally.
The general flow of begin/rescue/else/ensure/end looks like this:
begin
# something which might raise an exception
rescue SomeExceptionClass => some_variab...
What does “=>” mean in PHP?
...Note that this can be used for numerically indexed arrays too.
Example:
$foo = array('car', 'truck', 'van', 'bike', 'rickshaw');
foreach ($foo as $i => $type) {
echo "{$i}: {$type}\n";
}
// prints:
// 0: car
// 1: truck
// 2: van
// 3: bike
// 4: rickshaw
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Why check both isset() and !empty()
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This is completely redundant. empty is more or less shorthand for !isset($foo) || !$foo, and !empty is analogous to isset($foo) && $foo. I.e. empty does the reverse thing of isset plus an additional check for the truthiness of a value.
Or in other words, empty is the same as !$foo, but d...
Coroutine vs Continuation vs Generator
.... As @zvolkov mentioned, they're functions/objects that can be repeatedly called without returning, but when called will return (yield) a value and then suspend their execution. When they're called again, they will start up from where they last suspended execution and do their thing again.
A genera...