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Is there a standard function to check for null, undefined, or blank variables in JavaScript?
... ) {
}
will evaluate to true if value is not:
null
undefined
NaN
empty string ("")
0
false
The above list represents all possible falsy values in ECMA-/Javascript. Find it in the specification at the ToBoolean section.
Furthermore, if you do not know whether a variable exists (that means, if ...
How to debug Lock wait timeout exceeded on MySQL?
...nnoDB tables.
Since you know the query, all the tables being accessed are candidates for being the culprit.
From there, you should be able to run SHOW ENGINE INNODB STATUS\G
You should be able to see the affected table(s)
You get all kinds of additional Locking and Mutex Information.
Here is a sampl...
java.lang.OutOfMemoryError: GC overhead limit exceeded [duplicate]
... of thousands) HashMap objects with a few (15-20) text entries each. These Strings have all to be collected (without breaking up into smaller amounts) before being submitted to a database.
...
Query EC2 tags from within instance
... use a combination of the AWS metadata tool (to retrieve your instance ID) and the new Tag API to retrieve the tags for the current instance.
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How to use wait and notify in Java without IllegalMonitorStateException?
...d doSomething();.
Further, you have observer or listener named onResponse(String resp) that will be called by BlackBoxClass after unknown time.
The flow is simple:
private String mResponse = null;
...
BlackBoxClass bbc = new BlackBoxClass();
bbc.doSomething();
...
@override
public void onRe...
How do I get the collection of Model State Errors in ASP.NET MVC?
...
This will give you one string with all the errors with comma separating
string validationErrors = string.Join(",",
ModelState.Values.Where(E => E.Errors.Count > 0)
.SelectMany(E => E.Errors)
...
How do you switch pages in Xamarin.Forms?
...Type)
{
var viewName = viewModelType.FullName.Replace("Model", string.Empty);
var viewAssemblyName = GetTypeAssemblyName(viewModelType);
var viewTypeName = GenerateTypeName("{0}, {1}", viewName, viewAssemblyName);
return Type.GetType(viewTypeName);
}
publ...
Access props inside quotes in React JSX
...
The string enclosed by backticks is a "template literal": developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…
– Jon Schneider
Feb 15 '18 at 16:51
...
What's the reason I can't create generic array types in Java?
... the code generated by new ArrayList<SomeType>() or new ArrayList<String>() or new ArrayList() at all.
– newacct
Mar 26 '14 at 0:05
8
...
How to use Bash to create a folder if it doesn't already exist?
...
First, in bash "[" is just a command, which expects string "]" as a last argument, so the whitespace before the closing bracket (as well as between "!" and "-d" which need to be two separate arguments too) is important:
if [ ! -d /home/mlzboy/b2c2/shared/db ]; then
mkdir -p...