Life is grand - Latest Comments in Remove array item

Re: Remove array item

Paul Watson — Mon, 17 Jul 2006 13:46:05 -0000

And if it doesn't have it, prototype it :)

Re: Remove array item

David Stone — Mon, 17 Jul 2006 13:43:58 -0000

Andrew: Here's the JS Array Object documentation that lists what functions Array does have. As you can see, map is in there. And I think reduce is kinda like every: http://developer.mozilla.or...

Re: Remove array item

Andrew Peace — Sun, 16 Jul 2006 17:19:20 -0000

Eek, that didn't look so good - not sure how to get in this message board.

Re: Remove array item

Andrew Peace — Sun, 16 Jul 2006 17:18:29 -0000

The filter operation is quite cool - Python has something identical.

I'm not sure if javascript also has them, but a couple of other useful Python functions on sequences are map and reduce, which behave like:

def map(fn, list):
newlist = []
for item in list:
newlist.append = fn(item)

def reduce(fn ,list, initial_arg = None):
if initial_arg:
val = initial_arg
start = 0
else:
val = list[0]
start = 1

for i in range(start, len(list)):
val = fn(val, myseq[i])
return val

I may have goofed these up as I did them off the top of my head, but hopefully you get the idea.

Re: Remove array item

David Stone — Fri, 14 Jul 2006 16:46:17 -0000

Better:

Array.prototype.remove = function(item_to_remove)
{
var index;
while((index = this.indexOf(item_to_remove)) != -1)
{
this.splice(index, 1);
}
return this;
}

That way you can do:

var filtered = [1, 2, 3, 4, 5, 6, 5, 7, 8, 5, 9, 10].remove(5);
document.write(filtered);

Re: Remove array item

David Stone — Fri, 14 Jul 2006 16:40:42 -0000

Here. This:

Array.prototype.remove = function(item_to_remove)
{
var index;
while((index = this.indexOf(item_to_remove)) != -1)
{
this.splice(index, 1);
}
}

That'll remove all of the items that match. For instance:

var filtered = [1, 2, 3, 4, 5, 6, 5, 7, 8, 5, 9, 10];
filtered.remove(5);
document.write(filtered);

1,2,3,4,6,7,8,9,10

Re: Remove array item

David Stone — Fri, 14 Jul 2006 15:55:17 -0000

But is that really better than the iteration and the splice?

Re: Remove array item

Paul Watson — Fri, 14 Jul 2006 12:21:02 -0000

Ah yeah, damn, invalid assignment. Hmmmm... So it can be used outside of a prototype extension but not inside. Grr.

Maybe you could do this.clear and then this.push(this.filter blah blah

Re: Remove array item

David Stone — Fri, 14 Jul 2006 12:15:17 -0000

You'd think...but setting this = this.filter... actually results in an error because you're not allowed to re-assign to this.

Re: Remove array item

Paul Watson — Fri, 14 Jul 2006 04:19:02 -0000

hhmm didn't know about Array.filter. Seems quite nice, though I wonder about performance?

And I reckon it could be used, just use this = this.filter(func);.

Re: Remove array item

David Stone — Thu, 13 Jul 2006 17:24:24 -0000

I'd tend to say that using the Array.filter method would be a cleaner way of doing it...but filter doesn't change the actual array, so you couldn't use that.