jQuery specify criteria for searching value in array

Question

In javascript I need to know if array contains value. Values are objects and I can have different instances of same object, which means $.inArray(...) will not work. I know how to do my task using $.each(...) and my question is - is it possible to pass function with value's comparing logic to any of jQuery methods (see sample with desired sintax)?

    // values
var val1 = { id: 1, description: 'First value'};
var val2 = { id: 2, description: 'Second value'};
var val3 = { id: 3, description: 'Third value'};        
// array of values
var values = [ val1, val2, val3 ];
// inArray of jQuery to know if value is in array -> returns TRUE
var isInArray = $.inArray(val2, values) > -1;

// another instance of same object "val2"
var val2_anotherInstance = { id: 2, description: 'Second value'};
// inArray works as expected -> returns FALSE but desirable result is TRUE
var isInArray_anotherInstance = $.inArray(val2_anotherInstance, values) > -1;

// define function for comparing values (any logic can be implemented, for example searching by Id)
var valueComparer = function(first, second) {
    return first.id == second.id && first.description == second.description;
}
// function compares objects and returns true for different instances
alert(valueComparer(val2, val2_anotherInstance));

// desirable sintax:
// is something like this possible ???      
// NOTE next line not correct
isInArray_anotherInstance = $.inArray(val2_anotherInstance, values, valueComparer) > -1;
// actually what I want is specify criteria for searching value in array

Unfortunately inArray() doesn't take a function. You could use grep() — elclanrs
– elclanrs, Commented Apr 19, 2012 at 8:05

Community · Accepted Answer · 2017-05-23 11:49:05Z

2

Try grep:

var val1 = { id: 1, description: 'First value'};
var val2 = { id: 2, description: 'Second value'};
var val3 = { id: 3, description: 'Third value'};        

var values = [ val1, val2, val3 ];

// another instance of same object "val2"
var val2_anotherInstance = { id: 2, description: 'Second value'};


var items = $.grep(values, function(x) {
    return x.id == val2_anotherInstance.id
})

var found = items.length > 0

For more elegance, you can use a boolean aggregator function, as provided in this answer:

val2_in_array = $.some(values, function() {
    return this.id == val2_anotherInstance.id
});

edited May 23, 2017 at 11:49

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answered Apr 19, 2012 at 8:05

georg

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Comments

Alexey Pavlov · Accepted Answer · 2012-04-19 09:11:35Z

1

You may use this function for your task:

$.fn.inArrayCallback = function(needle, haystack, f) {
  var e = -1;
  $.each(haystack,function(index, value){
      if (f(needle,value)) { e = index; return false; }
    });
  return e;
}

ans = $.fn.inArrayCallback(val2_anotherInstance, values, valueComparer) > -1; 
// returns true

Answer with grep function will search all elements in array, even if matched element is already found. This function stops searching on match. This may be significant on very big arrays.

edited Apr 19, 2012 at 9:11

answered Apr 19, 2012 at 8:42

Alexey Pavlov

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1 Comment

georg Over a year ago

re:your edit - that's why I also suggested some(), which stops as soon as the callback returns true.

Samich · Accepted Answer · 2012-04-19 08:05:30Z

0

You can use greep() function to filter your array and then take count of the items in produced array. But it will handle all of the array and if you have a lot of data it will be not performance friendly.

answered Apr 19, 2012 at 8:05

Samich

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Comments

Ahamed Mustafa M · Accepted Answer · 2012-04-19 08:16:53Z

0

jquery map function should solve your problem. You can implement your comparison logic in the callback of map. refer jQuery map

answered Apr 19, 2012 at 8:16

Ahamed Mustafa M

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