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How to detect if a function is called as constructor?
...structor = true;
this.__previouslyConstructedByX = true;
}
alert(isConstructor);
}
Obviously this is not ideal, since you now have an extra useless property on every object constructed by x that could be overwritten, but I think it's the best you can do.
(*) "instance of" is an in...
Getting a better understanding of callback functions in JavaScript
...) {
// "this" may be different depending how you call the function
alert(this);
};
callback(argument_1, argument_2);
callback.call(some_object, argument_1, argument_2);
callback.apply(some_object, [argument_1, argument_2]);
The method you choose depends whether:
You have the arguments...
Pass Variables by Reference in Javascript
... = "goodbye";
}
var myObj = { foo: "hello world" };
alterObject(myObj);
alert(myObj.foo); // "goodbye" instead of "hello world"
You can iterate over the properties of an array with a numeric index and modify each cell of the array, if you want.
var arr = [1, 2, 3];
for (var i = 0; i < arr....
How to tell if a tag failed to load
...
<script src="nonexistent.js" onerror="alert('error!')"></script> fiddle
– Rudey
Feb 17 '17 at 10:48
...
What is the difference between typeof and instanceof and when should one be used vs. the other?
...
A good reason to use typeof is if the variable may be undefined.
alert(typeof undefinedVariable); // alerts the string "undefined"
alert(undefinedVariable instanceof Object); // throws an exception
A good reason to use instanceof is if the variable may be null.
var myNullVar = null;
ale...
What is the JavaScript convention for no operation?
...on is:
none of your suggestions, instead do:
var a = 2;
if (a === 1)
alert(1)
// else do nothing!
then the code is easily understandable, readable and as much efficient as it can get.
Why make it more difficult, when it can be simple?
edit:
So then, does a "no-operation" command basica...
How do I get the different parts of a Flask request's url?
...
another example:
request:
curl -XGET http://127.0.0.1:5000/alert/dingding/test?x=y
then:
request.method: GET
request.url: http://127.0.0.1:5000/alert/dingding/test?x=y
request.base_url: http://127.0.0.1:5000/alert/dingding/test
request.url_c...
rails i18n - translating text with links inside
...f Rails.env.test?
nil
end
end
In the controller:
flash.now[:alert] = t("path.to.translation")
flash.now[:alert_link] = here_comes_the_link_path # or _url
In the locale.yml:
path:
to:
translation: "string with __link__ in the middle"
In the view:
<%= render_flash_message...
What does = +_ mean in JavaScript
...how use of =+ to convert a string into int.
example:
y = +'5'
x = y +5
alert(x);
outputs 10
use: So here y is int 5 because of =+
otherwise:
y = '5'
x = y +5
alert(x);
outputs 55
Where as _ is a variable.
_ = + '5'
x = _ + 5
alert(x)
outputs 10
Additionally,
It would be interesting...
How do I count a JavaScript object's attributes? [duplicate]
... (var k in foo) {
if (foo.hasOwnProperty(k)) {
++count;
}
}
alert("Found " + count + " properties specific to foo");
The second line shows how other code can add properties to all Object derivatives. If you remove the hasOwnProperty() check inside the loop, the property count will g...