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Note that this algorithm is O(n^2).
– Gumbo
Commented Oct 18, 2009 at 8:54
9

Let [a, b, c] and [x, b, d] be the arrays (assume quotes). concat gives [a, b, c, x, b, d]. Wouldn't the unique()'s output be [a, c, x, b, d]. That doesn't preserve the order I think - I believe OP wants [a, b, c, x, d]
– Amarghosh
Commented Oct 18, 2009 at 9:04
10

I originally up-voted this but have changed my mind. Assigning prototypes to Array.prototype has the consequences of breaking "for ... in" statements. So the best solution is probably to use a function like this but not assign it as a prototype. Some people may argue that "for ... in" statements shouldn't be used to iterate array elements anyway, but people often use them that way so at the very least this solution be used with caution.
– Code Commander
Commented Feb 2, 2011 at 0:49
17

you should always use for ... in with hasOwnProperty in which case the prototype method is fine
– mulllhausen
Commented Jan 1, 2013 at 12:17
2

Just use Babel and Set() as described in another answer.
– cmcculloh
Commented May 4, 2016 at 20:32

| Show 17 more comments

Correct minor typos or mistakes
Clarify meaning without changing it
Add related resources or links
Always respect the author’s intent
Don’t use edits to reply to the author

create code fences with backticks ` or tildes ~
```
like so
```
add language identifier to highlight code
```python
def function(foo):
print(foo)
```
put returns between paragraphs
for linebreak add 2 spaces at end
_italic_ or **bold**
indent code by 4 spaces
backtick escapes `like _so_`
quote by placing > at start of line
to make links (use https whenever possible)
<https://example.com>
[example](https://example.com)
<a href="https://example.com">example</a>

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