Finding neighbours in a two-dimensional array

Question

Is there an easy way of finding the neighbours (that is, the eight elements around an element) of an element in a two-dimensional array? Short of just subtracting and adding

Answer 1

In javascript

    let arr = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

        function getNeighborsNumbersAtIthJth(i, j) {
            let allPosibleIndexes = [
                [i - 1, j],
                [i, j - 1],
                [i - 1, j - 1],
                [i + 1, j],
                [i, j + 1],
                [i + 1, j + 1],
                [i + 1, j - 1],
                [i - 1, j + 1]
            ];
            let allPosibleValues = []
            allPosibleIndexes.forEach(([i, j]) => {
                try {
                    allPosibleValues.push(arr[i][j])
                } catch (err) {

                }
            })
            return allPosibleValues.filter(v => v != undefined);
        }
        console.log(getNeighborsNumbersAtIthJth(1, 1));//[2, 4, 1, 8, 6, 9, 7, 3]
        console.log(getNeighborsNumbersAtIthJth(0, 1));//[1, 5, 3, 6, 4]
        console.log(getNeighborsNumbersAtIthJth(0, 0));//[4, 2, 5]