javascript - Trying to apply a filter to a nested array full of objects

Question

I have a resources array which is full of objects. Each object has categories array full of objects. I am trying to apply a filter to only return resources that have category objects of a specific name. I am having some trouble with the nesting of my data object.

Here is the data I am working with:

const resources = [
  {
    title: 'Learn JS',
    categories: [
      {
        name: 'javascript'
      },
      {
        name: 'css'
      }
    ]
  },
  {
    title: 'Learn CSS',
    categories: [
      {
        name: 'css'
      }
    ]
  },
  {
    title: 'Learn other stuff',
    categories: [
      {
        name: 'jQuery'
      },
      {
        name: 'javascript'
      }
    ]
  },
  {
    title: 'Learn node',
    categories: [
      {
        name: 'node'
      }
    ]
  },
  {
    title: 'Learn React',
    categories: [
      {
        name: 'react'
      }
    ]
  },

];

Here are my two attempts. Both return empty arrays. Am I wrong to be trying to use maps and filters. Is a for loop necessary?

//GOAL: Return only the resources that have a category with name 'javascript'
const attemptOne = resources.filter((item) => {
  return item.categories.forEach((thing, index) => {
    return thing[index] === 'javascript'
  });
}).map((item) => {
  return item;
})

const attemptTwo = resources.filter((item) => {
  item.categories.filter((ci) => {
    return ci.name === 'javascript'
  }).map((nextItem) => {
    return nextItem;
  });
})

I have been stumbling around with this for a while, and I am not sure if I am just over complicating it our what. Thanks in advance!

Answer 1

You can use filter on resources. Inside the filter, since you already know that an object has categories, you can just use some to check if the category name you are looking for is included

const resources = [{
  title: 'Learn JS',
  categories: [{
    name: 'javascript'
  }, {
    name: 'css'
  }]
}, {
  title: 'Learn CSS',
  categories: [{
    name: 'css'
  }]
}, {
  title: 'Learn other stuff',
  categories: [{
    name: 'jQuery'
  }, {
    name: 'javascript'
  }]
}, {
  title: 'Learn node',
  categories: [{
    name: 'node'
  }]
}, {
  title: 'Learn React',
  categories: [{
    name: 'react'
  }]
}];

function filterViaCategory(arr, category) {
  return arr.filter(obj => obj.categories.some(cat => cat.name === category));
}

console.log(filterViaCategory(resources, 'javascript'));