Comparing two data in javascript

Question

I'm fetching data from a soccer live API every minute using AWS for automation. I'd like to compare the new data with the old one. Each piece of data is an Array, so two JavaScript Arrays will be compared.

If there is a change in a new value, this value will be shown to the user at the Vue.js front-end. For example, the user will be alerted when shot on target rises to 4 from 3.

However, I'm struggling with that algorithm. Which libraries or functions will solve my problem?

How does the data structure look like? Is it always the same? — frhd, Nov 30 '18 at 16:03
https://stackoverflow.com/questions/7837456/how-to-compare-arrays-in-javascript? — Pete, Nov 30 '18 at 16:03
@Pete thanks for answer but i would like to know which value that is changed. Of course, two array will also compare each other first then we have to know which value is changed. — Quicksilver, Nov 30 '18 at 16:08
Possible duplicate of [How to compare arrays in JavaScript?](https://stackoverflow.com/questions/7837456/how-to-compare-arrays-in-javascript) — Reza Nasiri, Nov 30 '18 at 16:44

score 0 · Accepted Answer · answered Nov 30 '18 at 16:16

It is more like you want to know the delta between two exactly same javascript structures. When I want to find out delta I generally use deep-object-diff. It has multiple difference functions.

From the example from npmjs:

const lhs = {
  foo: {
    bar: {
      a: ['a', 'b'],
      b: 2,
      c: ['x', 'y'],
      e: 100 // deleted
    }
  },
  buzz: 'world'
};

const rhs = {
  foo: {
    bar: {
      a: ['a'], // index 1 ('b')  deleted
      b: 2, // unchanged
      c: ['x', 'y', 'z'], // 'z' added
      d: 'Hello, world!' // added
    }
  },
  buzz: 'fizz' // updated
};

console.log(detailedDiff(lhs, rhs));

/*
{
  added: {
    foo: {
      bar: {
        c: {
          '2': 'z'
        },
        d: 'Hello, world!'
      }
    }
  },
  deleted: {
    foo: {
      bar: {
        a: {
          '1': undefined
        },
        e: undefined
      }
    }
  },
  updated: {
    buzz: 'fizz'
  }
}
*/

wow thanks for reply. I really didnt know that. I will inform you if i can do it or not. — Quicksilver, Nov 30 '18 at 16:21
reason for the downvote? Op asked `Which libraries` and I gave what I use — Aritra Chakraborty, Nov 30 '18 at 17:02

Comparing two data in javascript

1 Answers1