Angularjs get indexOf through filter

Question

I have a set of JSON data returned by the backend API, and i need to loop through existing array and get the index to be used in splice, thus i am using indexOf method combined with the filter function from angular.

I am able to filter the data out from existing array, however i am unable to get the index of the array, it returned -1.

This is how do it.

JS

angular.forEach($scope.data, function(){
   var index = $scope.Tablelist.indexOf($filter('filter')($scope.Tablelist,{id: $scope.data.id},true));
   console.log($filter('filter')($scope.Tablelist,{id: $scope.data.id},true));
   console.log(index);
})

castletheperson · Accepted Answer · 2016-05-18 06:23:05Z

3

$filter returns an array, from which you need to get the first element, and then search with indexOf:

var index = $scope.Tablelist.indexOf(
                $filter('filter')($scope.Tablelist,{id: $scope.data.id},true)[0]
            );

However, I would just use Array.prototype.findIndex(). It will be much faster, since it won't iterate the Tablelist more than it needs to.

var index = $scope.Tablelist.findIndex(function(item) {
    return item.id === $scope.data.id;
});

Or a regular for loop if you want better browser compatibility:

var index = -1;
for (var i = 0; i < $scope.Tablelist.length; i++)
    if ($scope.Tablelist[i].id === $scope.data.id) {
        index = i;
        break;
    }
}

edited May 18, 2016 at 6:23

answered May 18, 2016 at 6:03

castletheperson

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3 Comments

Joseph Over a year ago

care to explain why you would use findIndex instead of filter?

castletheperson Over a year ago

For speed. With the filter method, it will iterate the Tablelist twice. Once to find the correct item with the filter, and again in the indexOf. With findIndex it will only iterate once, and it will only be until it finds the first match.

castletheperson Over a year ago

A warning actually. I just realized that findIndex isn't supported in IE or Opera. You might be better off just using a for loop with a break when it finds a match.

Raghav Patel · Accepted Answer · 2016-05-21 07:24:19Z

2

Try this:

var object = $filter('filter')($scope.Tablelist, function (d) {
   return d.id === $scope.data.id;
})[0]
console.log(object);
console.log($scope.Tablelist.indexOf(object);

edited May 21, 2016 at 7:24

answered May 18, 2016 at 5:59

Raghav Patel

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Comments

Dylan Watt · Accepted Answer · 2016-05-18 05:59:12Z

1

$filter('filter')($scope.Tablelist,{id: $scope.data.id},true)

Returns a an array of length 1, not the item itself.

$filter('filter')($scope.Tablelist,{id: $scope.data.id},true)[0]

may do the trick

answered May 18, 2016 at 5:59

Dylan Watt

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Comments

YetAnotherCoder · Accepted Answer · 2016-05-18 05:59:16Z

1

$filter returns an array, you are trying to find index of that array in your Tablelist which returns -1, try:

var index =
  $scope.Tablelist.indexOf($filter('filter')($scope.Tablelist,{id: $scope.data.id},true)[0]));

answered May 18, 2016 at 5:59

YetAnotherCoder

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