Array of objects with some objects containing another array, need to filter it by values within the object containing an array

Question

Sorry for the long title question didn't know how to properly formulate my question.

So this is the question, I got an array which stores objects, and within those objects there's another array with the key tags and which is an array that gets filled with tags.

Object:

var arr = new Array;

arr[0] = {
            "like": 0,
            "dislike": 0,
            "answer": "body",
            "tags" : ["offline", "facebook"],
            "comments" : []
        };

arr[1] = {
            "like": 0,
            "dislike": 0,
            "answer": "body",
            "tags" : ["school", "online"],
            "comments" : []
        };

arr[2] = {
        "like": 0,
        "dislike": 0,
        "answer": "body",
        "tags" : ["school", "offline"],
        "comments" : []
    };

The [0], [1] indexes respresent and ID, but that isn't really important here.

The problem is when I try to filter it with(I know it only tries to filter arr[0] atm but I will write a loop so it goes through all the indexes):

var toFind = "offline";

var filtered = arr[0].filter(function(el) {
  return el.tags === toFind;
});

console.log(filtered);

It says arr[0].filter is not a function, but got no idea why it thinks arr[0] should be taken into account as a function.

When I remove the [0] it gives back a blank array...

So my question is how can I get the .filter function to give back the complete object based on tags in the tags array. So that if I search for the tag "school" it gives back arr[1] and arr[2], the complete objects.

Hope I my question is crystal clear and that I provided enough information. If you guys need anymore information, feel free to ask me for it. Or if you want me to clarify things, just ask :)

Hope you guys can help me!

Answer 1

Refering to the documention : https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter?v=control

you shall use :

var arr = new Array;

arr[0] = {
            "like": 0,
            "dislike": 0,
            "answer": "body",
            "tags" : ["offline", "facebook"],
            "comments" : []
        };


var toFind = "offline";
//I'm filtering on arr[0].tags directly !! 
var filtered = arr[0].tags.filter(function(el) { 

  return el === toFind;
});

console.log(filtered);

Answer 2

Like has been said, arr[0] points to an object, which doesn't have a filter method. You need to call filter on the array itself

 var tagToFind = "school"; var arr = new Array; arr[0] = { "like": 0, "dislike": 0, "answer": "body", "tags" : ["offline", "facebook"], "comments" : [] }; arr[1] = { "like": 0, "dislike": 0, "answer": "body", "tags" : ["school", "online"], "comments" : [] }; arr[2] = { "like": 0, "dislike": 0, "answer": "body", "tags" : ["school", "offline"], "comments" : [] }; var filtered = arr.filter(function(item){ return item.tags && //to account for undefined tags properties item.tags.includes(tagToFind); //if you're supporting IE you will need to look and check each element instead }); console.log(filtered); 

Answer 3

If I am interpreting your question correctly, it appears that you want something along the lines of

arr.forEach((a) => {
    if (a["tags"].includes(toFind))
        console.log(a);
});

This will loop through each element of arr and check that the tags array contains toFind (and prints out the object if it does).

Answer 4

if you want to do it for the whole array then try this

 var arr = new Array;
 arr[0] = {
        "like": 0,
        "dislike": 0,
        "answer": "body",
        "tags" : ["offline", "facebook"],
        "comments" : []
    };

  arr[1] = {
        "like": 0,
        "dislike": 0,
        "answer": "body",
        "tags" : ["school", "online"],
        "comments" : []
    };

   arr[2] = {
    "like": 0,
    "dislike": 0,
    "answer": "body",
    "tags" : ["school", "offline"],
    "comments" : []
};
var filtered = arr.filter(function(el) {
  return el.tags.find(function (entity){
    return entity===toFind;
  });
});

 console.log(filtered);