JS Array findIndex() is not a function

Question

The following code produces always an error:

var index = this.dataSource.findIndex(item => item.id_system === row.id_system);

The error message is: TypeError: this.dataSource.findIndex is not a function

What could be the solution?

Answer 1

If you're using Angular Material example, then you will need to use data array.

Your dataSource should be MatTableDataSource<your type> .

So maybe you can try

let index = this.dataSource.data.findIndex(item => item.id_system === row.id_system);