Javascript filter object using includes

Question

I'm trying to filter an object using the filter() function in javascript .

I want to filter againts an array like this: [1615, 1616]. It's referenced in the code as value.verdier.

Dataset is a large array holding objects that have several properties, parsed from a JSON string. Each object in the array has a property named kat_id.

The goal is to reduce the array so that it only holds objects where kat_id=1615 or kat_id=1616. Or any other value that I have in value.verdier.

My code is like this:

dataset = dataset.filter(function (el) 
     {
        return value.verdier.includes(el.kat_id );
     });

I'm problably missing something really obvious.

Yes, I see that the question was poorly written. I shall edit it. — johnohod
– johnohod, Commented Jun 4, 2020 at 7:12

T.J. Crowder · Accepted Answer · 2020-06-04 08:00:41Z

The goal is to reduce the array so that it only holds objects where kat_id=1615 or kat_id=1616. Or any other value that I have in value.verdier.

The code in your question will do that, if the kat_id values and the values in value.verdier are all numbers or all strings. That's because includes does a === between the thing you pass into it and the entries in the array you call it on. So [1, 2, 3].includes("2") is false, as is ["1", "2", "3"].includes(2).

I assume you wouldn't be posting the question if it were working, though, so I assume the type of the values of kat_id and the type of the values in value.verdier are different — one of them is a number, the other is a string.

If the kat_id values are strings and the value.verdier values are numbers, you need to parse kat_id to number before using includes:

return value.verdier.includes(parseInt(el.kat_id, 10));

Live Example:

var value = {
    verdier: [1615, 1616]
};

var dataset = [
    {kat_id: "1", expected: "omit"},
    {kat_id: "2", expected: "omit"},
    {kat_id: "1615", expected: "retain"},
    {kat_id: "3", expected: "omit"},
    {kat_id: "1616", expected: "retain"},
    {kat_id: "4", expected: "omit"},
    {kat_id: "5", expected: "omit"},
];
dataset = dataset.filter(function (el) 
{
    return value.verdier.includes(parseInt(el.kat_id, 10));
});
console.log(dataset);

Or if the kat_id values are numbers and the value.verdier values are strings, you need to convert the kat_id numbers to strings before using includes:

return value.verdier.includes(String(el.kat_id));

Live Example:

var value = {
    verdier: ["1615", "1616"]
};

var dataset = [
    {kat_id: 1, expected: "omit"},
    {kat_id: 2, expected: "omit"},
    {kat_id: 1615, expected: "retain"},
    {kat_id: 3, expected: "omit"},
    {kat_id: 1616, expected: "retain"},
    {kat_id: 4, expected: "omit"},
    {kat_id: 5, expected: "omit"},
];
dataset = dataset.filter(function (el) 
{
    return value.verdier.includes(String(el.kat_id));
});
console.log(dataset);

If the values vary (some kat_ids are strings and others are numbers, and/or some value.verdier values are strings and others are numbers), you probably need some rather than includes and a type-insensitive comparison:

return value.verdier.some(function(val) { return String(val) === String(el.kat_id); });

Live Example:

var value = {
    verdier: [1615, "1616"]
};

var dataset = [
    {kat_id: "1", expected: "omit"},
    {kat_id: 2, expected: "omit"},
    {kat_id: "1615", expected: "retain"},
    {kat_id: "3", expected: "omit"},
    {kat_id: 1616, expected: "retain"},
    {kat_id: "4", expected: "omit"},
    {kat_id: 5, expected: "omit"},
];
dataset = dataset.filter(function (el) 
{
    return value.verdier.some(function(val) { return String(val) === String(el.kat_id); });
});
console.log(dataset);

I've stuck with ES5-level code above because your question seemed to be using ES5-level code only. But here are those examples using ES2015+:

dataset = dataset.filter(el => value.verdier.includes(parseInt(el.kat_id, 10)));

const value = {
    verdier: [1615, 1616]
};

let dataset = [
    {kat_id: "1", expected: "omit"},
    {kat_id: "2", expected: "omit"},
    {kat_id: "1615", expected: "retain"},
    {kat_id: "3", expected: "omit"},
    {kat_id: "1616", expected: "retain"},
    {kat_id: "4", expected: "omit"},
    {kat_id: "5", expected: "omit"},
];
dataset = dataset.filter(el => value.verdier.includes(parseInt(el.kat_id, 10)));
console.log(dataset);

dataset = dataset.filter(el => value.verdier.includes(String(el.kat_id)));

const value = {
    verdier: ["1615", "1616"]
};

let dataset = [
    {kat_id: 1, expected: "omit"},
    {kat_id: 2, expected: "omit"},
    {kat_id: 1615, expected: "retain"},
    {kat_id: 3, expected: "omit"},
    {kat_id: 1616, expected: "retain"},
    {kat_id: 4, expected: "omit"},
    {kat_id: 5, expected: "omit"},
];
dataset = dataset.filter(el => value.verdier.includes(String(el.kat_id)));
console.log(dataset);

dataset = dataset.filter(el => value.verdier.some(val => String(val) === String(el.kat_id)));

const value = {
    verdier: [1615, "1616"]
};

let dataset = [
    {kat_id: "1", expected: "omit"},
    {kat_id: 2, expected: "omit"},
    {kat_id: "1615", expected: "retain"},
    {kat_id: "3", expected: "omit"},
    {kat_id: 1616, expected: "retain"},
    {kat_id: "4", expected: "omit"},
    {kat_id: 5, expected: "omit"},
];
dataset = dataset.filter(el => value.verdier.some(val => String(val) === String(el.kat_id)));
console.log(dataset);

Thanks a lot for the incredibly friendly and helpful answer! Yes el.kat_id was a string, parseInt did fix the issue.
@johnohod - I'm really glad that helped! It was the only thing I could think of that would account for what you were describing. Happy coding!

takrishna · Accepted Answer · 2020-06-03 14:05:02Z

1

Here is a working sample:

function isInRefList(value) {
  let refList = [5, 44, 560];
  return refList.includes(value); //returns boolean
}

var myarr = [12, 5, 8, 130, 44];
myarr = [12, 5, 8, 130, 44].filter(isInRefList);

console.log(myarr); //Prints filtered array

answered Jun 3, 2020 at 14:05

takrishna

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