JavaScript/jQuery equivalent of LINQ Any()
Solution 1
These days you could actually use Array.prototype.some
(specced in ES5) to get the same effect:
array.some(function(item) {
return notValid(item);
});
Solution 2
You could use variant of jQuery is
function which accepts a predicate:
$(array).is(function(index) {
return notValid(this);
});
Solution 3
Xion's answer is correct. To expand upon his answer:
jQuery's .is(function)
has the same behavior as .NET's IEnumerable.Any(Predicate<T>)
.
From http://docs.jquery.com/is:
Checks the current selection against an expression and returns true, if at least one element of the selection fits the given expression.
Solution 4
You might use array.filter (IE 9+ see link below for more detail)
[].filter(function(){ return true|false ;}).length > 0;
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter
Solution 5
You should use an ordinary for
loop (not for ... in
), which will only loop through array elements.
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dilbert
Updated on July 05, 2022Comments
-
dilbert almost 2 years
Is there an equivalent of
IEnumerable.Any(Predicate<T>)
in JavaScript or jQuery?I am validating a list of items, and want to break early if error is detected. I could do it using
$.each
, but I need to use an external flag to see if the item was actually found:var found = false; $.each(array, function(i) { if (notValid(array[i])) { found = true; } return !found; });
What would be a better way? I don't like using plain
for
with JavaScript arrays because it iterates over all of its members, not just values. -
Groo about 13 yearsI believe OP wanted to say with plain
for
(...) iterates over all of its members that use offor in
can sometimes yield unexpected results (ifArray.prototype
is extended, or if you implicitly resize arrays). -
Groo about 13 yearsactually,
$.grep()
is more likeFindAll(Predicate<T>)
. -
Erick Petrucelli about 13 years@Groo: I didn't said that
Any(Predicate<T>)
is the most closest method togrep()
, only is very near. I agree thatFindAll(Predicate<T>)
is much more close to it. But both are near. -
aruno almost 11 years*could (I think you meant to say)
-
SLaks almost 11 years@Simon_Weaver: No; he should not use
for in
to iterate arrays. -
Mariano Desanze almost 11 yearsI think you should avoid using
this
inside theis
function when used for anarray
. Because you won't get the original type (so comparission using "===" will fail). I'd usearray[i]
instead. See this: jsfiddle.net/BYjcu/3 -
Chris Haines about 10 years@SLaks, you have misunderstood Simon_Weaver's comment! "You could use an ordinary for loop." Rather than "You should..."
-
aruno about 9 yearsquick summary:
some()
executes the callback function once for each element present in the array until it finds one where callback returns a true value. If such an element is found,some()
immediately returns true. Otherwise,some()
returns false. -
Ed Bishop about 8 yearsThis is the right answer if you can use it. It is an equivalent function to Linq.Any()
-
mlhDev over 7 yearsThis is interesting (my fiddle to confirm) but my gut reaction is to avoid this approach since it is operating a selection function
$.fn.is
over a collection that is not a jQuery selection (a native array). If there was a utility function like$.is
I'd feel safer, but this appears to be an undocumented "feature" -
Xion over 7 yearsAFAIK jQuery selections are native arrays (or at least they use
Array.prototype
), and there is probably enough code in the wild relying on it that it can never change. This saying, this answer is almost six years old. These days you should be using native ES5 approach shown nearby, or something like LoDash/Underscore/etc. that has API specifically for dealing with native JS arrays. -
mlhDev over 7 yearsYou're right, I did not notice the date on this answer. Sorry about that (and now I can't undo my downvote!)
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Akira Yamamoto almost 7 yearsIf you need IE8 compatibility, then this is not an option.
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Hardrada over 3 yearsUpdate: In ES6 / ECMAScript 2015, you can do
myArray.some(c=>c)
to mimic exactly what LINQ does with .Any(). Noting that in LINQ the .Any() method doesn't require a delegate, whereas .some() does. Attempting to call .some() without a delegate will result in an error as the delegate will be undefined. -
Kissaki over 2 yearsWas this supposed to be a comment or edit on their answer? It seems to only agree with that answer, adding a bit of context?
-
Kissaki over 2 yearsWell it definitely says should right there in the text. You can’t say they were misunderstood when it is literally written there.