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Fastest way to duplicate an array in JavaScript - slice vs. 'for' loop
...
There are at least 6 (!) ways to clone an array:
loop
slice
Array.from()
concat
spread operator (FASTEST)
map A.map(function(e){return e;});
There has been a huuuge BENCHMARKS thread, providing following information:
for blink browsers slice() is the fastest method, concat() is a bit slower, and...
How do I concatenate two arrays in C#?
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How is that more efficient than x.Concat(y)? It works and all, I'm just wondering if there is something that makes it better?
– Mike Two
Oct 10 '09 at 7:07
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How do I truncate a .NET string?
...rmance testing is fun: (using linqpad extension methods)
var val = string.Concat(Enumerable.Range(0, 50).Select(i => i % 10));
foreach(var limit in new[] { 10, 25, 44, 64 })
new Perf<string> {
{ "newstring" + limit, n => new string(val.Take(limit).ToArray()) },
{ "c...
Update MongoDB field using value of another field
...lection.<update method>(
{},
[
{"$set": {"name": { "$concat": ["$firstName", " ", "$lastName"]}}}
]
)
MongoDB 3.4+
In 3.4+ you can use $addFields and the $out aggregation pipeline operators.
db.collection.aggregate(
[
{ "$addFields": {
"name": {...
Is there an easy way to return a string repeated X number of times?
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If you're using .NET 4.0, you could use string.Concat together with Enumerable.Repeat.
int N = 5; // or whatever
Console.WriteLine(string.Concat(Enumerable.Repeat(indent, N)));
Otherwise I'd go with something like Adam's answer.
The reason I generally wouldn't advise ...
Why doesn't nodelist have forEach?
...to mean that the instance was an Array in combination with Array.prototype.concat.
There was a bug in Google's Closure Library which caused almost all Google's apps to fail due to this. The library was updated as soon as this was found but there might still be code out there that makes the same inco...
How can I append a string to an existing field in MySQL?
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You need to use the CONCAT() function in MySQL for string concatenation:
UPDATE categories SET code = CONCAT(code, '_standard') WHERE id = 1;
share
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How to extend an existing JavaScript array with another array, without creating a new array
...ed for "JavaScript array extend" and got here, you can very well use Array.concat.
var a = [1, 2, 3];
a = a.concat([5, 4, 3]);
Concat will return a copy the new array, as thread starter didn't want. But you might not care (certainly for most kind of uses this will be fine).
There's also some n...
How can I combine multiple rows into a comma-delimited list in Oracle? [duplicate]
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Just make sure your concatenated results don't exceed the VARCHAR2 max length limit of your oracle database (most likely 4000 bytes) otherwise you will run into ORA-01489 result of string concatenation is too long.
– JanM
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How to split strings across multiple lines in CMake?
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CMake 3.0 and newer
Use the string(CONCAT) command:
set(MYPROJ_VERSION_MAJOR "1")
set(MYPROJ_VERSION_MINOR "0")
set(MYPROJ_VERSION_PATCH "0")
set(MYPROJ_VERSION_EXTRA "rc1")
string(CONCAT MYPROJ_VERSION "${MYPROJ_VERSION_MAJOR}"
"...