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Ruby: kind_of? vs. instance_of? vs. is_a?
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kind_of? and is_a? are synonymous.
instance_of? is different from the other two in that it only returns true if the object is an instance of that exact class, not a subclass.
Example:
"hello".is_a? Object and "hello".kind_of? Object return true because "hello" is a String and String...
How to check if array element exists or not in javascript?
...ood of JS
Thus, they have the prototype method hasOwnProperty "inherited" from Object
in my testing, hasOwnProperty can check if anything exists at an array index.
So, as long as the above is true, you can simply:
const arrayHasIndex = (array, index) => Array.isArray(array) && array.h...
Converting Stream to String and back…what are we missing?
...string to the original bytes
look at Convert.ToBase64String and Convert. FromBase64String
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How does the “this” keyword work?
...not called on an object, ThisBinding is set to window.
This is different from Python, in which accessing a method (obj.myMethod) creates a bound method object.
var obj = {
myMethod: function () {
return this; // What is `this` here?
}
};
var myFun = obj.myMethod;
console.log("...
How do the post increment (i++) and pre increment (++i) operators work in Java?
... in the addition and then increment it to 6 (current value 6). Increment a from current value 6 to 7 to get other operand of +. Sum is 12 and current value of a is 7. Next increment a from 7 to 8 (current value = 8) and add it to previous sum 12 to get 20.
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How to use ternary operator in razor (specifically on HTML attributes)?
...esource_en.Department_View_DescartChanges)
</a>
if the text is not from App string Resources use this
@(Model.ID == 0 ? "Back" :"Descart Changes")
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Why can't I forward-declare a class in a namespace using double colons?
... still wouldn't work, because you can't declare a class within a namespace from outside that namespace. You have to be in the namespace.
So, you can in fact forward declare a class within a namespace. Just do this:
namespace Namespace
{
class Class;
};
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How do I create an HTML table with a fixed/frozen left column and a scrollable body?
...r anyone who is interested. Essentially the solution moves the headers off from the table and set each of them a 5em width. The table itself is pushed to the right for the same 5em width. This makes a visual appearance that the headers are still part of the normal flow in the table.
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Java - JPA - @Version annotation
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Although @Pascal answer is perfectly valid, from my experience I find the code below helpful to accomplish optimistic locking:
@Entity
public class MyEntity implements Serializable {
// ...
@Version
@Column(name = "optlock", columnDefinition = "intege...
What are the “standard unambiguous date” formats for string-to-date conversion in R?
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This is documented behavior. From ?as.Date:
format: A character string. If not specified, it will try
'"%Y-%m-%d"' then '"%Y/%m/%d"' on the first non-'NA' element,
and give an error if neither works.
as.Date("01 Jan 2000") ...