How do i filter an array inside of a array of objects?

Question

I'm trying to filter a list by tags:

const initialState = [
     {id:1 ,name: 'Product A', image: 'pic-001.jpg', tags: ['nature', 'camping', 'outdoor']},
     {id:2 ,name: 'Product B', image: 'pic-002.jpg', tags: ['winter', 'hiking', 'camping', 'snow']},
     {id:3 ,name: 'Product C', image: 'pic-003.jpg', tags: ['vacation', 'family', 'kids', 'river', 'lake', 'fishing']}
   ]

I can filter the list by name using map and filter, my problem is when i try to list the products by tags. Do i have to use foreach inside of my products filter? There's another way of doing it?

I don't think there is any other way of doing it. You will have to iterate through the array for your condition of matching with tags. — kvn
– kvn, Commented Jul 6, 2017 at 13:07

sjahan · Accepted Answer · 2017-07-10 12:44:37Z

16

Like that?

const filter = 'nature';
const filteredResult = initialState.filter((item) => {
    return (item.tags.indexOf(filter) >= 0);
});

edited Jul 10, 2017 at 12:44

answered Jul 6, 2017 at 13:10

sjahan

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5 Comments

pishpish Over a year ago

Why not use includes?

sjahan Over a year ago

@destoryer what's includes? It may be a feature from lodash or underscore, but I think it's not native JS.

pishpish Over a year ago

includes not supported by IE though.

sjahan Over a year ago

That's nice to know about, I thought it was from an utility lib! Nice :)

Takebo Over a year ago

some how i had to convert to string for it to work. Otherwise it was buggy, not sure why. return (item.tags.toString().indexOf(tag) >= 0);. Thanks guys, and sorry for the late reply!

Ori Drori · Accepted Answer · 2018-09-26 07:03:32Z

9

You can create a Set of selected tags, and use Array#some to check if at least one of the tags in the Set exists in the objects' tags list:

const initialState = [
     {id:1 ,name: 'Product A', image: 'pic-001.jpg', tags: ['nature', 'camping', 'outdoor']},
     {id:2 ,name: 'Product B', image: 'pic-002.jpg', tags: ['winter', 'hiking', 'camping', 'snow']},
     {id:3 ,name: 'Product C', image: 'pic-003.jpg', tags: ['vacation', 'family', 'kids', 'river', 'lake', 'fishing']}
];

const filterByTags = ['nature', 'family'];

const filterByTagSet = new Set(filterByTags);

const result = initialState.filter((o) => 
  o.tags.some((tag) => filterByTagSet.has(tag))
);

console.log(result);

edited Sep 26, 2018 at 7:03

answered Jul 6, 2017 at 13:14

Ori Drori

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1 Comment

Steven Over a year ago

Just what I needed

Daniel Erez · Accepted Answer · 2017-07-06 13:14:16Z

1

you can use indexOf function

var foo = initialState.filter(function(elm){
  return elm.tags.indexOf("camping")>=0
});

answered Jul 6, 2017 at 13:14

Daniel Erez

384 bronze badges

Comments

Calvin · Accepted Answer · 2017-07-07 03:23:10Z

Firstly to get all the tags and filter the duplicate tags from initialState. Save the array into uniqueTags.

Then compare the uniqueTags with initialState names, to create another array productTags with objects and its properties tags and products.

const initialState = [
     {id:1 ,name: 'Product A', image: 'pic-001.jpg', tags: ['nature', 'camping', 'winter', 'outdoor']},
     {id:2 ,name: 'Product B', image: 'pic-002.jpg', tags: ['winter', 'hiking', 'family', 'camping', 'snow']},
     {id:3 ,name: 'Product C', image: 'pic-003.jpg', tags: ['vacation', 'family', 'kids', 'river', 'lake', 'fishing']}
   ]

   let allTags = [];
   initialState.map((t)=>t.tags).forEach((a)=>a.forEach((b)=>allTags.push(b)))
   let uniqueTags = allTags.filter((a,i,arr)=>arr.indexOf(a,i+1)===-1)


   productTags = [];
   uniqueTags.forEach((u)=>{
       initialState.forEach((t)=>{
           if(t.tags.includes(u))
            productTags.push({'tag': u, 'product':t.name});
       })
   })


   console.log(JSON.stringify(productTags));

   /*
   [
    { "tag": "nature", "product": "Product A" }, 
    { "tag": "outdoor", "product": "Product A" }, 
    { "tag": "winter", "product": "Product A" }, 
    { "tag": "winter", "product": "Product B" }, 
    { "tag": "hiking", "product": "Product B" }, 
    { "tag": "camping", "product": "Product A" }, 
    { "tag": "camping", "product": "Product B" }, 
    { "tag": "snow", "product": "Product B" }, 
    { "tag": "vacation", "product": "Product C" }, 
    { "tag": "family", "product": "Product B" }, 
    { "tag": "family", "product": "Product C" }, 
    { "tag": "kids", "product": "Product C" }, 
    { "tag": "river", "product": "Product C" }, 
    { "tag": "lake", "product": "Product C" }, 
    { "tag": "fishing", "product": "Product C" }
] */

(Edited later) Correction:

To form the correct object, I have changed the code to:

const initialState = [
     {id:1 ,name: 'Product A', image: 'pic-001.jpg', tags: ['nature', 'camping', 'winter', 'outdoor']},
     {id:2 ,name: 'Product B', image: 'pic-002.jpg', tags: ['winter', 'hiking', 'family', 'camping', 'snow']},
     {id:3 ,name: 'Product C', image: 'pic-003.jpg', tags: ['vacation', 'family', 'kids', 'river', 'lake', 'fishing']}
   ]

   let allTags = [];
   initialState.map((t)=>t.tags).forEach((a)=>a.forEach((b)=>allTags.push(b)))
   let uniqueTags = allTags.filter((a,i,arr)=>!arr.includes(a,i+1))


   productTags = [];
   uniqueTags.forEach((u)=>{
       let productName = [];
       initialState.forEach((t)=>{
           if(t.tags.includes(u))
            productName.push(t.name);
       })
       productTags.push({tag:u, products:productName}); 
   })

   console.log(JSON.stringify(productTags));

   /*
    productTags = [
        {"tag":"nature","products":["Product A"]},
        {"tag":"outdoor","products":["Product A"]},
        {"tag":"winter","products":["Product A","Product B"]},
        {"tag":"hiking","products":["Product B"]},
        {"tag":"camping","products":["Product A","Product B"]},
        {"tag":"snow","products":["Product B"]},
        {"tag":"vacation","products":["Product C"]},
        {"tag":"family","products":["Product B","Product C"]},
        {"tag":"kids","products":["Product C"]},
        {"tag":"river","products":["Product C"]},
        {"tag":"lake","products":["Product C"]},
        {"tag":"fishing","products":["Product C"]}
    ] 
    */

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