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What is the difference between null and undefined in JavaScript?
...null;
alert(TestVar); //shows null
alert(typeof TestVar); //shows object
From the preceding examples, it is clear that undefined and null are two distinct types: undefined is a type itself (undefined) while null is an object.
null === undefined // false
null == undefined // true
null === null // ...
Get current time in milliseconds in Python?
...ution to the second, the preferred approach for milliseconds is datetime.
from datetime import datetime
dt = datetime.now()
dt.microsecond
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How to generate a random number in C++?
...y of one element - the first element of a pseudo-random sequence generated from seed equal to current time of second precision. What do you expect to see on output then?
Obviously when you happen to run application on the same second - you use the same seed value - thus your result is the same of co...
CSS3 Transparency + Gradient
...le */
background-image: -webkit-gradient(
linear, left top, left bottom, from(rgba(50,50,50,0.8)),
to(rgba(80,80,80,0.2)), color-stop(.5,#333333)
);
(src)
/* mozilla example - FF3.6+ */
background-image: -moz-linear-gradient(
rgba(255, 255, 255, 0.7) 0%, rgba(255, 255, 255, 0) 95%
);
(src...
HashMap with multiple values under the same key
...dd(new Person("Bob Jones"));
peopleByForename.put("Bob", people);
// read from it
List<Person> bobs = peopleByForename["Bob"];
Person bob1 = bobs[0];
Person bob2 = bobs[1];
The disadvantage with this approach is that the list is not bound to exactly two values.
2. Using wrapper class
// d...
Is LINQ to SQL Dead or Alive?
...e friends with LINQ to SQL, it appears as though MS is pulling the rug out from under it.
16 Answers
...
Where is PATH_MAX defined in Linux?
...
Beware: PATH_MAX is different from NAME_MAX (and the x-ref'd article in part seems to confuse these two, at least in part). Note: POSIX <limits.h> says: A definition of one of the symbolic constants in the following list shall be omitted from the &l...
Update one MySQL table with values from another
I'm trying to update one MySQL table based on information from another.
2 Answers
2
...
Drop unused factor levels in a subsetted data frame
...- factor(subdf$letters)
> subdf$letters
[1] a b c
Levels: a b c
EDIT
From the factor page example:
factor(ff) # drops the levels that do not occur
For dropping levels from all factor columns in a dataframe, you can use:
subdf <- subset(df, numbers <= 3)
subdf[] <- lapply(subd...
DisplayName attribute from Resources?
... it is possible to have the DisplayName for a certain model property set from a Resource.
6 Answers
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