Get specific item from array in jquery

Question

I am working on a array in my code . My array contains mutliple boolean . I want to check that if a single false exists in my array then it returns false otherwise true . I did following

var results = self.resultCollection();

    for (var i = 0; i < results.length ; i++) {

        if (!results[i]) {
            self.isModelValid = false;
            break;
        } else {
            self.isModelValid = true;
        }
    }

Now i hear from somebody that there is some thing in jquery call grap or may be grasp , i am not confirmed . He told me that that grap/grasp will give you that thing in one line . Anyone knows about that .

Thanks in advance .

it is grep , look: api.jquery.com/jQuery.grep

Ivan Chernykh
– Ivan Chernykh

2013-06-09 06:50:14 +00:00
Commented Jun 9, 2013 at 6:50 — Ivan Chernykh
– Ivan Chernykh, Commented Jun 9, 2013 at 6:50

Blender · Accepted Answer · 2013-06-09 06:54:47Z

2

Just use indexOf:

var results = self.resultCollection();
self.isModelValid = (results.indexOf(false) === -1);

Or if you really need that extra dose of jQuery:

self.isModelValid = ($.inArray(false, results) === -1);

This'll only work if the value is actually false, not falsey (0, an empty string, etc.).

answered Jun 9, 2013 at 6:54

Blender

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2 Comments

kirelagin Over a year ago

What if the OP is looking for falsy values, but not exactly false? In this sense your code is not a drop-in replacement.

Blender Over a year ago

@kirelagin: OP explicitly mentioned booleans, so I would assume that they're actually true/false.

Community · Accepted Answer · 2017-05-23 12:28:58Z

1

var results = self.resultCollection();
self.isModelValid = $.grep(results, function(n){return n}).length == results.length;

If the length of the filtered array returned by $.grep is the different from the original array, that means that at least one of the item is false. When they aren't the same, self.isModelValid will also be false, creating the effect you want.

Explanation

$.grep(results, function(n){return n})

$.grep removes all false values and returns a new array using the filter return n (only returning true items).

$.grep(results, function(n){return n}).length == results.length

The new array's length is then compared to the original array's length. If they are different, that means that at least one item is false and removed. If their lengths are the same, this will returns true. false if they are different.

self.isModelValid = ...

The boolean is then assigned to self.isModelValid.

$.grep works, but it might not be the best practice in your case. jQuery will try to evaluate the whole array and returning a new one, increasing the performance cost. Use Blender's code if your array only contains booleans.

On the other hand, if your array contains multiple types and you are already using jQuery, this might be the best way to do it.

edited May 23, 2017 at 12:28

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answered Jun 9, 2013 at 6:54

Derek 朕會功夫

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7 Comments

kirelagin Over a year ago

That's really-really bad, it doesn't short-circuit.

Derek 朕會功夫 Over a year ago

@kirelagin - What I was asking is what do you mean it doesn't short-circuit?

kirelagin Over a year ago

@Derek朕會功夫 I mean that you always evaluate the whole collection. Not to mention that you are creating a new one, as large as the collection in question.

Derek 朕會功夫 Over a year ago

@kirelagin - I thought he would want to know more about grep that's why I used it in my example.

Ancient Over a year ago

@Derek朕會功夫 thats look better . Thanks for favor .

|

kirelagin · Accepted Answer · 2013-06-09 06:59:52Z

0

every could help here but it is pure JavaScript, not jQuery.

self.isModelValid = results.every(function(x){return x;});

edited Jun 9, 2013 at 6:59

answered Jun 9, 2013 at 6:53

kirelagin

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2 Comments

Ancient Over a year ago

what if i have false in middle and true at last index . I think in this case it will return true

kirelagin Over a year ago

@user2413182 What made you think so?

user1259089 · Accepted Answer · 2013-06-09 07:21:07Z

0

try this
var results = self.resultCollection();
self.isModelValid = (results.indexOf(false) === -1);

answered Jun 9, 2013 at 7:21

user1259089

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