Scan NdArray in row-major oder.

scan.js

const nj = require('numjs');

function scan(ndarr, cb) {
    const args = Array(ndarr.shape.length).fill(0);
    function _scan(ndarr, cb) {
        const shape = ndarr.shape;
        const argi = args.length - shape.length;
        for (args[argi] = 0; args[argi] < shape[0]; ++args[argi]) {
            if (shape.length > 1) {
                const d = ndarr.pick(args[argi]);
                _scan(d, cb);
            } else {
                cb(...args);
            }
        }
    }
    _scan(ndarr, cb);
}