How to solve a problem with Array.sort Cannot assign to read only property '0' of object

Question

In my React App I'm getting an error in the sort functionality

Uncaught TypeError: Cannot assign to read only property '0' of object '[object Array]'

I have no idea what the problem is and the functionality is this:

const preparedSites = useMemo(
      () =>
        sites
          .sort(sortSiteSelection(site))
          .map(elm => {
            const arr = [
              elm.siteId,
              elm.city,
              elm.state,
              elm.country,
              elm.address,
              elm.status,
            ];
            if (nearestSites.length)
              arr.push(
                nearestSites.find(s => s.closestSiteId === elm.siteId).distance,
              );
            return arr;
          })
          .sort((a, b) => a[6] - b[6]),
      [sites, site, nearestSites],
    );

The error happening on the .sort part and the ´sortSiteSelection´ is as follow

const nameCompare = (x, y) => x.name.localeCompare(y.name);
const cityCompare = (x, y) => x.city.localeCompare(y.city);
const compareCountry = s => (x, y) => {
  if (!s) return 0;

  if (x.countryCode === s.countryCode && y.countryCode === s.countryCode)
    return 0;
  else if (x.countryCode === s.countryCode) return -1;
  else if (y.countryCode === s.countryCode) return 1;
  else return x.countryCode.localeCompare(y.countryCode);
};

export const sortSiteSelection = selectedSite => {
  if (!selectedSite) {
    console.log('NULL FROM SORT SITE');
    return () => 0;
  }
  pipeSort(compareCountry(selectedSite), nameCompare, cityCompare);
};

The OBJ of site is just

{
 siteId,
 city,
 elm.state,
 country,
 address,
 status,

}

Athii · Accepted Answer · 2021-02-18 08:54:39Z

30

I would say it's because the array is in strict mode. You should create a copy of this array. There are multiple ways for that.

[...sites].sort(sortSiteSelection(site))

or

sites.slice().sort(sortSiteSelection(site))

I hope this solves the issue you're facing

answered Feb 18, 2021 at 8:54

Athii

6698 silver badges22 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Jakub Over a year ago

I tried both ways but still have this issue Uncaught TypeError: Cannot assign to read only property '0' of object '[object Array]' at Array.sort (<anonymous>)

Jakub Over a year ago

Error was fixed somehow was an error in different places where other sorts where used and adding this fixed the issue

Collectives™ on Stack Overflow

How to solve a problem with Array.sort Cannot assign to read only property '0' of object

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related