sudoku validator

sudoku-validator.js

function validate(board) {
    const input = getArray(board);
    const predicates = [
        hasValidStructure,
        createDataValidator([9, 1]),
        createDataValidator([1, 9]),
        createDataValidator([3, 3])
    ];

    const isValid = predicates.every(fn => fn(input));
    return isValid;
}

function hasValidStructure(data) {
    if (!Array.isArray(data)) {
        return false;
    }
    for (let row of data) {
        if (!Array.isArray(row) || !row.every(isValid)) {
            return false;
        }
    }
    return true;
}

function createDataValidator(size = [3, 3]) {
    return (data) => {
        for (let index of range(0, 9)) {
            if (!isUnique(slice(data, index, size))) {
                return false;
            }
        }
        return true;
    }
}

function* range(from, to) {
    while (from < to) {
        yield from++;
    }
}

function* pick(data, row, col) {
    for (let i of row()) {
        for (let j of col()) {
            yield data[i][j];
        }
    }
}

function* slice(data, index, size = [3, 3], width = 9) {
    const s = (index * size[0]);
    const row = ((s / width) | 0) * size[1];
    const col = (s % width);
    yield* pick(data, () => range(row, row + size[1]), () => range(col, col + size[0]));
}

function isUnique(data) {
    let array = Array.from(data).filter(entry => entry !== null).map(entry => +entry);
    return (new Set(array).size === array.length);
}

function isValid(entry) {
    return (entry === null) || (+entry === (entry|0)) && (entry > 0 && entry < 10);
}

function getArray(data) {
    try {
        return (Array.isArray(data)) ? data : JSON.parse(data);
    } catch (e) {}
}