CODEWITHSUNDEEP
javascriptarraysecmascript-6
FeRcHo
FeRcHo

Reputation: 1151

compare two object arrays by javascript keys

I am working with javascript I have two arrangements that for the example look like this:

const arr1 = [
    { url: 1, 'title': 'A', 'title2': 'A2' },
    { url: 2, 'title': 'B', 'title2': 'B2' },
    { url: 3, 'title': 'C', 'title2': 'C2' },
    { url: 4, 'title': 'D', 'title2': 'D2' },
    { url: 5, 'title': 'E', 'title2': 'E2' },
]

const arr2 = [
    { url: 1, 'title': 'A', 'title2': 'J2' },
    { url: 2, 'title': 'J', 'title2': 'B2' },
    { url: 3, 'title': 'C', 'title2': 'C2' },
    { url: 4, 'title': 'D', 'title2': 'D2' },
    { url: 5, 'title': 'K', 'title2': 'E2' },
]

I would like to obtain from the second array those objects that are different either the title or title2

I tried the following but it doesn't work for me, where am I getting lost?

const res = arr2.filter((page1) => !arr1.some(page2 => page1.title === page2.title || page2.title2 == page1.title2 ))

the expected result is this for the example:

[{ url: 1, 'title': 'A', 'title2': 'J2' },{"url":2,"title":"J","title2":"B2"},{"url":5,"title":"K","title2":"E2"}]

Upvotes: 0

Views: 76

Answers (4)

Siva Kondapi Venkata
Siva Kondapi Venkata

Reputation: 11001

Build an object to track the titles based on arr1 and use same object to filter arr2

const arr1=[{url:1,title:"A",title2:"A2"},{url:2,title:"B",title2:"B2"},{url:3,title:"C",title2:"C2"},{url:4,title:"D",title2:"D2"},{url:5,title:"E",title2:"E2"}];

const arr2=[{url:1,title:"A",title2:"J2"},{url:2,title:"J",title2:"B2"},{url:3,title:"C",title2:"C2"},{url:4,title:"D",title2:"D2"},{url:5,title:"K",title2:"E2"}];

const track = {};
arr1.forEach(({ url, title, title2 }) =>
  Object.assign(track, { [url]: { [title]: title2 } })
);

const results = arr2.filter(
  ({ url, title, title2 }) => track?.[url]?.[title] !== title2
);

console.log(results)

Upvotes: 0

epascarello
epascarello

Reputation: 207501

Easiest is to map the one to a look up and loop over the second.

const arr1 = [
    { url: 1, 'title': 'A', 'title2': 'A2' },
    { url: 2, 'title': 'B', 'title2': 'B2' },
    { url: 3, 'title': 'C', 'title2': 'C2' },
    { url: 4, 'title': 'D', 'title2': 'D2' },
    { url: 5, 'title': 'E', 'title2': 'E2' },
];

const arr2 = [
    { url: 1, 'title': 'A', 'title2': 'J2' },
    { url: 2, 'title': 'J', 'title2': 'B2' },
    { url: 3, 'title': 'C', 'title2': 'C2' },
    { url: 4, 'title': 'D', 'title2': 'D2' },
    { url: 5, 'title': 'K', 'title2': 'E2' },
];

const arr1MapByUrl = arr1.reduce((acc, data) => {
  acc[data.url] = data;
  return acc;
}, {});

const results = arr2.filter(data => {
  const org = arr1MapByUrl[data.url];
  return !org || data.title !== org.title || data.title2 !== org.title2;
});

console.log(results);

If you do not want to hard code the keys to check, you can loop over them with some() and compare them.

const arr1 = [
    { url: 1, 'title': 'A', 'title2': 'A2' },
    { url: 2, 'title': 'B', 'title2': 'B2' },
    { url: 3, 'title': 'C', 'title2': 'C2' },
    { url: 4, 'title': 'D', 'title2': 'D2' },
    { url: 5, 'title': 'E', 'title2': 'E2' },
];

const arr2 = [
    { url: 1, 'title': 'A', 'title2': 'J2' },
    { url: 2, 'title': 'J', 'title2': 'B2' },
    { url: 3, 'title': 'C', 'title2': 'C2' },
    { url: 4, 'title': 'D', 'title2': 'D2' },
    { url: 5, 'title': 'K', 'title2': 'E2' },
];

const arr1MapByUrl = arr1.reduce((acc, data) => {
  acc[data.url] = data;
  return acc;
}, {});

const results = arr2.filter(data => {
  const org = arr1MapByUrl[data.url];
  return !org || Object.entries(data).some(([key, value]) => org[key] !== value);
});

console.log(results);

Upvotes: 1

Nina Scholz
Nina Scholz

Reputation: 386560

You could collect all objects from array1 in an object by using url as key and filter the second array by checking title and title2.

const
    array1 = [{ url: 1, 'title': 'A', 'title2': 'A2' }, { url: 2, 'title': 'B', 'title2': 'B2' }, { url: 3, 'title': 'C', 'title2': 'C2' }, { url: 4, 'title': 'D', 'title2': 'D2' }, { url: 5, 'title': 'E', 'title2': 'E2' }],
    array2 = [{ url: 1, 'title': 'A', 'title2': 'J2' }, { url: 2, 'title': 'J', 'title2': 'B2' }, { url: 3, 'title': 'C', 'title2': 'C2' }, { url: 4, 'title': 'D', 'title2': 'D2' }, { url: 5, 'title': 'K', 'title2': 'E2' }],
    keys = ['title', 'title2'],
    urls = Object.fromEntries(array1.map(o => [o.url, o])),
    result = array2.filter(o => keys.some(k => o[k] !== urls[o.url][k]));

console.log(result);
.as-console-wrapper { max-height: 100% !important; top: 0; }

Upvotes: 1

Kinglish
Kinglish

Reputation: 23654

If I am understanding your goal, it is to first match URLs and THEN find out if there is a discrepency in the titles. If that is correct, this will get you there.

const res = arr2.filter(page1 => {
  // find URL match
  let page2 = arr1.find(f => f.url === page1.url) 
  return !page2 || page2.title != page1.title || page2.title2 != page1.title2;
})


const arr1 = [
    { url: 1, 'title': 'A', 'title2': 'A2' },
    { url: 2, 'title': 'B', 'title2': 'B2' },
    { url: 3, 'title': 'C', 'title2': 'C2' },
    { url: 4, 'title': 'D', 'title2': 'D2' },
    { url: 5, 'title': 'E', 'title2': 'E2' },
]

const arr2 = [
    { url: 1, 'title': 'A', 'title2': 'J2' },
    { url: 2, 'title': 'J', 'title2': 'B2' },
    { url: 3, 'title': 'C', 'title2': 'C2' },
    { url: 4, 'title': 'D', 'title2': 'D2' },
    { url: 5, 'title': 'K', 'title2': 'E2' },
]

const res = arr2.filter(page1 => {
  // find URL match
  let page2 = arr1.find(f => f.url === page1.url) 
  return !page2 || page2.title != page1.title || page2.title2 != page1.title2;
})
console.log(res)

Upvotes: 1

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