multi-array | easier way to safely access

The clear reason for the error you're getting is that your innermost arrays are initialized as empty. Accessing any index of an empty array would produce an exception.

You either initialize your array elements with a value...

In your function agregarComa and console.log, the argument grado seems to be an array of strings. If you want to join these strings with a comma and a space you can simply to this:

My first thought is to use a std::map instead of the vector. This way, you can search the map by calling find (example).

If the map gets bigger over time, you should consider switching to an std::unordered_map or maybe even to a database, instead of the file access (something like SQLite). This way, you use SQL-statements to filter by id, which is faster then loading and searching everything locally.

Because initial of coviddata is undefined. So coviddata.map will show this error. coviddata only change to array when api call success.

You just update decalre state with empty array:

First, build a list of the indexes to remove by seeing if the key exists in arr2. Then, return arr1 with those indexes filtered out of each element.

If you want to merge two arrays of objects according to the index:

• Check which one of the two is greater than the other, and set each to first and second accordingly (first should be iterated over to guarantee the element at index won't be undefined)
• Iterate over first using .map, and merge the two objects at each index

Using String.prototype.localeCompare, you can compare the string values and based on that result, using Array.prototype.sort function, you can sort the arrays as follows.

Unfortunately, I couldn't find the options for putting the nested JSON object as a table for importJson. So as a workaround, how about using the specific custom formula for the URL?

Please copy and paste the following script to the script editor of the Spreadsheet and save it.

You can access the contiguous element storage.

The prototype is

void cblas_dgemm( CBLAS_LAYOUT layout, CBLAS_TRANSPOSE TransA, CBLAS_TRANSPOSE TransB, const int M, const int N, const int K, const double alpha, const double *A, const int lda, const double *B, const int ldb, const double beta, double *C, const int ldc )

So, let's fill it in: