How can I return an array of objects whose property matches an array?

Question

I have an array like

array = [
  { name: "john", tag: ["tag1", "tag2"] },
  { name: "doe", tag: ["tag2"] },
  { name: "jane", tag: ["tag2", "tag3"] }
];

I want to get a new array of objects which contain both "tag2" and "tag3", but not only "tag2" or both "tag1" and "tag2".

Result should be:

newArray = [{ name: "jane", tag: ["tag2", "tag3"] }];

I tried to do it using this process:

tags = ["tag2", "tag3"];
newArray = [];
tags.forEach(t => {
  array.forEach(data => {
    data.tag.forEach(item => {
      if (item === t) {
        newArray.push(data);
      }
    });
  });
});

But I get all the items instead.

The posted question does not appear to include any attempt at all to solve the problem. StackOverflow expects you to try to solve your own problem first, as your attempts help us to better understand what you want. Please edit the question to show what you've tried, so as to illustrate a specific roadblock you're running into a minimal reproducible example. For more information, please see How to Ask and take the tour. — CertainPerformance
– CertainPerformance, Commented Dec 16, 2018 at 7:11

nem035 · Accepted Answer · 2018-12-16 07:49:36Z

If I understood you correctly, you want to search through your top-level array, to find all items whose tag property is an array exactly matching ['tag2', 'tag3'].

You can achieve this by filtering your array based on the above condition.

Here's one approach:

 
const array = [
  {
    name: 'john',
    tag: ['tag1', 'tag2']
  },
  {
    name: 'doe',
    tag: ['tag2']
  },
  {
    name: 'jane',
    tag: ['tag2', 'tag3']
  }
];

const tagsToMatchOn = ['tag2', 'tag3'];

// find all elements who's tag property exactly matches
// the above tags (in presence, not necessarily in order)
const newArray = array.filter(item => (
  item.tag.length === tagsToMatchOn.length && 
  tagsToMatchOn.every(t => item.tag.includes(t))
));

console.log(newArray);

If instead, you wanted to find all items whose tag property is an array including all of ['tag2', 'tag3'] but can also include other tags, you can try something like this:

const array = [
  {
    name: 'john',
    tag: ['tag1', 'tag2']
  },
  {
    name: 'doe',
    tag: ['tag2']
  },
  {
    name: 'jane',
    tag: ['tag2', 'tag3']
  }
];

const tagsToMatchOn = ['tag2', 'tag3'];

// find all elements who's tag property includes
// all of the above tags but can also contain others
const newArray = array.filter(item =>
  tagsToMatchOn.every(t => item.tag.includes(t))
);

console.log(newArray);

Andrew1325 · Accepted Answer · 2018-12-16 07:38:59Z

0

This mightn't be the most elegant solution but it does return what you want.

array = [{name:'john',
          tag: ['tag1','tag2'] 
         },
         {name:'doe',
          tag: ['tag2'] 
         },
         {name:'jane',
          tag: ['tag2','tag3'] 
         }
        ];

const newArray = [];
for (let index = 0; index < array.length; index++) {
    if(array[index].tag[0] === 'tag2' && array[index].tag[1] === 'tag3') {
        newArray.push(array[index])
    }
}

or if you want to be a bit more es6:

array.forEach(element => {
  if(element.tag[0] === 'tag2' && element.tag[1] === 'tag3') {
    newArray.push(element)
  }
});

edited Dec 16, 2018 at 7:38

answered Dec 16, 2018 at 7:33

Andrew1325

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1 Comment

nem035 Over a year ago

just a note, forEach isn't ES6, it's ES5.

Code Maniac · Accepted Answer · 2018-12-16 07:43:50Z

0

You can do it like this

With the help of filter and every.

What basically i am doing here is first i am lopping through each element of arr (using filter). by using every i am checking does the tag property to element contains all the tags we require. if it does than we include in our final output if not than we don't

let arr = [{name:'john',
          tag: ['tag1','tag2'] 
         },
         {name:'doe',
          tag: ['tag2'] 
         },
         {name:'jane',
          tag: ['tag2','tag3'] 
         }
        ];
let tags = ['tag2','tag3'];
let op = arr.filter(e=> tags.every(el=> e.tag.includes(el)));
console.log(op);

answered Dec 16, 2018 at 7:43

Code Maniac

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