Getting undefined error while processing array

Question

I have 2 arrays like below:

$scope.Stat.Statistics =[{val:10} , { val:11} , { val:13} ,{ val:14}]
$scope.selected = [{ val:12} , { val:13} ] //based on checkbox  selection

Now i just want to add selected value to Statistics array and remove those which doesnt exist in selected but ignoring 1st record of statistics.

Expected output

$scope.Stat.Statistics ={[ val:10]} , {[ val:12]} , {[ val:13]}

Code:

for (var i = 0; i < selected.length; i++) {
    for (var j = 1; j <= $scope.Stat.Statistics.length; j++) {
        //ignore 1st record for comparision
        if (selected[i].val != $scope.Stat.Statistics[j].val) {
            $scope.Stat.Statistics.splice(j, 1);
            $scope.Stat.Statistics[j].push(selected[i]);
        }
    }
}

Update:In case of same value in Statistics and selected i would like to keep statistics value.

Error:$scope.Stat.Statistics[j] is undefined

You just spliced out j, it doesn't exist in the array anymore — Sterling Archer
– Sterling Archer, Commented Oct 3, 2016 at 15:27
please verify that definition... : {[ val:10]} , {[ val:11]} , {[ val:13]} ,{[ val:14]}... could be [ { val:10}, { val:11}... ] — Joao Polo
– Joao Polo, Commented Oct 3, 2016 at 15:27
Where you define the arrays is not valid javascript. I think you meant $scope.Stat.Statistics = [ {val:10}, {val:11}, ...]; — forgivenson
– forgivenson, Commented Oct 3, 2016 at 15:27
@NinaScholz Sorry i was in little hurry to post question so that was a mistake.but updated my question and thanks for pointing out that mistake — I Love Stackoverflow
– I Love Stackoverflow, Commented Oct 3, 2016 at 15:31

nikjohn · Accepted Answer · 2016-10-03 20:07:47Z

2

$scope.Stat.Statistics ={[ val:10]} , {[ val:11]} , {[ val:13]} ,{[ val:14]}

This is not valid Javascript. If you want an array, you should be defining it like:

$scope.Stat.Statistics =[{val:10} , { val:11} , { val:13} ,{ val:14}]

var Statistics = [{
  val: 10
}, {
  val: 11
}, {
  val: 13
}, {
  val: 14
}];

var selected = [{
  val: 12
}, {
  val: 13
}];

var found = selected;
Statistics.map(function(statistic) {
  selected.map(function(selectedItem) {
    if(selectedItem.val === statistic.val) {
      found.push(selectedItem); 
    }
  });
});

console.log(found);

Of course, I've factored out the Angular element out of it, but this same logic should work.

edited Oct 3, 2016 at 20:07

answered Oct 3, 2016 at 15:28

nikjohn

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8 Comments

I Love Stackoverflow Over a year ago

Sorry i was in little hurry to post question so that was a mistake.but updated my question and thanks for pointing out that mistake

Sterling Archer Over a year ago

This answer is now invalid after the edit. Please remedy

I Love Stackoverflow Over a year ago

Your output is incorrect because everytime i need first record of statistics and all other records of selected and removing unmatched items from Statistics.So final output will be : 10,12,13

I Love Stackoverflow Over a year ago

When we will have common val from both statistics and selected then in that case i would like to preserve data from statistics

nikjohn Over a year ago

"When we will have common val from both statistics and selected then in that case i would like to preserve data from statistics": In that case shouldn't the output be 10, 13?

|

Nina Scholz · Accepted Answer · 2016-10-03 17:19:23Z

1

You could take the first element of $scope.Stat.Statistics, you want to keep and concat $scope.selected to the first element.

var $scope = { Stat: {} };

$scope.Stat.Statistics = [{ val: 10 }, { val: 11 }, { val: 13 }, { val: 14 }];
$scope.selected = [{ val: 12 }, { val: 13 }];
$scope.Stat.Statistics = [$scope.Stat.Statistics[0]].concat($scope.selected);

console.log($scope.Stat.Statistics);

Edit: keeping common items with same val and append the rest to the array.

var $scope = { Stat: {} },
    hash = {},
    i;

$scope.Stat.Statistics = [{ val: 10 }, { val: 11 }, { val: 13, extra: 42 }, { val: 14 }];
$scope.selected = [{ val: 12 }, { val: 13 }];

$scope.selected.forEach(function (a) {
    hash[a.val] = a;
});

i = $scope.Stat.Statistics.length;
while (i--) {
    if (hash[$scope.Stat.Statistics[i].val]) {
        delete hash[$scope.Stat.Statistics[i].val];
        continue;
    }
    if (i === 0) {
        continue;
    }
    $scope.Stat.Statistics.splice(i, 1);
}
Object.keys(hash).forEach(function (k) {
    $scope.Stat.Statistics.push(hash[k]);
});

console.log($scope.Stat.Statistics);

edited Oct 3, 2016 at 17:19

answered Oct 3, 2016 at 15:32

Nina Scholz

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6 Comments

I Love Stackoverflow Over a year ago

But i want to remove those value from statistics which doesnt exist in $scope.selected

Marc Over a year ago

@Learning And that's exactly what you will get. At the end $scope.Stat.Statistics will equal [{val:10} , { val:12} , { val:13}]

I Love Stackoverflow Over a year ago

Ok this is working fine but will it be possible that suppose if i have val i.e 13 which is common in both so is that case i would like to preserve it instead of overwriting 13 with selectedvalue

Nina Scholz Over a year ago

you couold keep common values, but with fany filtering, you get the same, if the object inside of the arrays are really identical.

I Love Stackoverflow Over a year ago

Actually objects are identical but but i have 2 extra properties in Statictics which i would like to preserve in case of same value in both the array.

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