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App Inventor 2 扩展 · App Inventor 2 中文网
...em in private versions of App Inventor that are hosted and managed individually.
App Inventor Extensions let anyone create Extension Components. Extension components can be used in building projects, just like other components. The difference is that extension components can be distributed on th...
Formula to determine brightness of RGB color
...Note that both of these emphasize the physiological aspects: the human eyeball is most sensitive to green light, less to red and least to blue.
– Bob Cross
Feb 27 '09 at 19:28
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MongoDB: How to query for records where field is null or not set?
...ount({sent_at: {$exists: false}})
If its there and null, or not there at all:
db.emails.count({sent_at: null})
Refer here for querying and null
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Is it possible to do a sparse checkout without checking out the whole repository first?
...mand, no need to run git pull
Note that it requires git version 2.25 installed. Read more about it here: https://github.blog/2020-01-17-bring-your-monorepo-down-to-size-with-sparse-checkout/
UPDATE:
The above git clone command will still clone the repo with its full history, though without check...
How can I unit test Arduino code?
I'd like to be able to unit test my Arduino code. Ideally, I would be able to run any tests without having to upload the code to the Arduino. What tools or libraries can help me with this?
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String.Join method that ignores empty strings?
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I had some luck with this instead: Array.FindAll(myArray, Function(s) Not String.IsNullOrEmpty(s)) Can you either change your answer or explain the Where statement?
– Doug
May 2 '13 at 13:44
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How to make a DIV visible and invisible with JavaScript
...ffects:
Adjusting style.display will look as if element is not present at all ("removed").
elem.style.display = 'none'; // hide
elem.style.display = 'block'; // show - use this for block elements (div, p)
elem.style.display = 'inline'; // show - use this for inline elements (span, a)
or style.vi...
Framework vs. Toolkit vs. Library [duplicate]
... Inversion of Control.
What does this mean? Well, it means that when you call a library, you are in control. But with a framework, the control is inverted: the framework calls you. (This is called the Hollywood Principle: Don't call Us, We'll call You.) This is pretty much the definition of a frame...
Submit jQuery UI dialog on
...ned, which means if the dialog is opened twice, the event handler will be called twice.
– Elezar
Apr 29 '14 at 23:32
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Programmatically open Maps app in iOS 6
...ordinate2DMake(16.775, -3.009);
MKPlacemark *placemark = [[MKPlacemark alloc] initWithCoordinate:coordinate
addressDictionary:nil];
MKMapItem *mapItem = [[MKMapItem alloc] initWithPlacemark:placemark];
[mapItem setName:@"My Place"];
// Pas...