Javascript: How to use map and filter between two array object

Question

I am facing some issue on using .map and .filter where I am unable to get the object which is not similar in two objects. What changes I need to do to get the uncommon object from arrayObjTwo.

code

const arrayObjOne = [{
          countryCode: "US",
          description: " Backyard of home",
          id: "1234",
          location: "US",
          name: "Backyard",
          }]
// Array Object 2
const arrayObjTwo =[
    { description: "Backyard of home", spaceName: "Backyard" },
    { description: "Frontyard of home", spaceName: "Frontyard"},
]
const object1Names = arrayObjOne.map(obj => obj.Name); // for caching the result
const results = arrayObjTwo.filter(name => !object1Names.includes(name));
console.log(results);

One compiler code: https://onecompiler.com/javascript/3xy92hpmp

expected result:

const arrayObjTwo =[
        { description: "Frontyard of home", spaceName: "Frontyard" }
    ]

Thanks..

It's a little confusing when you ask about object2 and there's nothing called object2 in your code. Your question would be more clear if you referred to things by the same name in your question text and in your code. — Wyck
– Wyck, Commented Apr 6, 2022 at 5:41

Amats · Accepted Answer · 2022-04-06 05:46:32Z

Your filter for the result is wrong. You should be using the "object.spaceName" instead of just "name" as you're looping through an array of objects and not just strings

// So this line:
const results = arrayObjTwo.filter(name => !object1Names.includes(name));

// Should be:
const results = arrayObjTwo.filter(object => !object1Names.includes(object.spaceName));

// And you have a typo:
const object1Names = arrayObjOne.map(obj => obj.Name);

// Should be like so as keys and properties are case-sensitive:
const object1Names = arrayObjOne.map(obj => obj.name);

So this should all be:

const arrayObjOne = [{
          countryCode: "US",
          description: " Backyard of home",
          id: "1234",
          location: "US",
          name: "Backyard",
          }]
// Array Object 2
const arrayObjTwo =[
    { description: "Backyard of home", spaceName: "Backyard" },
    { description: "Frontyard of home", spaceName: "Frontyard"},
]
const object1Names = arrayObjOne.map(obj => obj.name); // for caching the result
const results = arrayObjTwo.filter(object => !object1Names.includes(object.spaceName));
console.log(results);

Sigve Hagesæter · Accepted Answer · 2022-04-06 05:45:15Z

You're close!

You have capitalized names in your map-statement, but javascript is case-sensitive, so the field you're looking up "Name", does not exist, and as such your "object1Names" returns undefined.

You should be looking up obj.name

You also need to compare it to the arrayObjTwo's "spaceName"-field, not the entire object.

Here's your code with these small changes:

const arrayObjOne = [{
          countryCode: "US",
          description: " Backyard of home",
          id: "1234",
          location: "US",
          name: "Backyard",
          }]
// Array Object 2
const arrayObjTwo =[
    { description: "Backyard of home", spaceName: "Backyard" },
    { description: "Frontyard of home", spaceName: "Frontyard"},
]
const object1Names = arrayObjOne.map(obj => obj.name); // for caching the result
const results = arrayObjTwo.filter(obj => !object1Names.includes(obj.spaceName));
console.log(results);

Deadpool · Accepted Answer · 2022-04-06 05:41:28Z

0

Do you need this?

const arr1 = [{
          countryCode: "US",
          description: " Backyard of home",
          id: "1234",
          location: "US",
          name: "Backyard",
          }]
// Array Object 2
const arr2 =[
    { description: "Backyard of home", spaceName: "Backyard" },
    { description: "Frontyard of home", spaceName: "Frontyard"},
]
const names = arr1.map(item => item.name); // for caching the result
console.log(names);
const res = arr2.filter(item => !names.includes(item.name));
console.log(res);

answered Apr 6, 2022 at 5:41

Deadpool

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