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How to avoid 'cannot read property of undefined' errors?
...has added support for optional chaining in version 3.7.
// use it like this
obj?.a?.lot?.of?.properties
Solution for JavaScript before ECMASCript 2020 or TypeScript older than version 3.7:
A quick workaround is using a try/catch helper function with ES6 arrow function:
function getSafe(fn, d...
What guarantees are there on the run-time complexity (Big-O) of LINQ methods?
...ds. Obviously, there are many factors at play here, so let's restrict the discussion to the plain IEnumerable LINQ-to-Objects provider. Further, let's assume that any Func passed in as a selector / mutator / etc. is a cheap O(1) operation.
...
Error - trustAnchors parameter must be non-empty
...
This bizarre message means that the truststore you specified was:
empty,
not found, or
couldn't be opened (due to access permissions for example).
See also @AdamPlumb's answer below.
To debug this issue (I wrote about it h...
Why fragments, and when to use fragments instead of activities?
... are the purposes of using a fragment & what are the
advantages and disadvantages of using fragments compared to using
activities/views/layouts?
Fragments are Android's solution to creating reusable user interfaces. You can achieve some of the same things using activities and layouts (for ...
Correct idiom for managing multiple chained resources in try-with-resources block?
...ources syntax (also known as ARM block ( Automatic Resource Management )) is nice, short and straightforward when using only one AutoCloseable resource. However, I am not sure what is the correct idiom when I need to declare multiple resources that are dependent on each other, for example a File...
Chrome doesn't delete session cookies
I'm trying to set session cookie in javascript like this:
13 Answers
13
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How to prevent logback from outputting its own status at the start of every log when using a layout
This seems like a carelessness error, but I can't seem to find the cause. Logging with logback/slf4j (most recent version slf4j-api-1.6.1, logback core/classic 0.9.24). Simplest log configuration for testing is:
...
How do I get the RootViewController from a pushed controller?
...ontroller = [viewControllers objectAtIndex:viewControllers.count - 2];
This is the standard way of getting the "back" view controller. The reason objectAtIndex:0 works is because the view controller you're trying to access is also the root one, if you were deeper in the navigation, the back view w...
How to find serial number of Android device?
...ELEPHONY_SERVICE);
String uid = tManager.getDeviceId();
getSystemService is a method from the Activity class. getDeviceID() will return the MDN or MEID of the device depending on which radio the phone uses (GSM or CDMA).
Each device MUST return a unique value here (assuming it's a phone). Thi...
Delete rows from a pandas DataFrame based on a conditional expression involving len(string) giving K
... delete rows from it where the length of the string in a particular column is greater than 2.
6 Answers
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