@lunaticmuch/front-matter-manipulator/lib/util/filterByField.js

A utility for parsing and manipulating documents with Front Matter

import getFieldPermutations  from './getFieldPermutations.js';
import getDescendantProp  from './getDescendantProp.js';

export default function filterByFields(filters, data, exclude) {
    var filtered = data.filter(function(data) {
        for (var i = 0; i < filters.length; i++) {
            if (exclude === true) {
                var isExcluded = excludeByField(filters[i], data);
                return isExcluded;
            } else {
                var isIncluded = includeByField(filters[i], data);
                return isIncluded;
            }
        }
    });

    return filtered;
}

function includeByField(filter, data) {
    if (!filter) throw new Error('Missing value for "filter"');
    if (!data) throw new Error('Missing value for "data"');

    var field = filter[0];
    var permutations = getFieldPermutations(field, data);
    var desiredValue = filter[1];
    var trueValues = permutations.map(function(p) {
        return getDescendantProp(data, p);
    });

    for (var i = 0; i < trueValues.length; i++) {
        var trueValue = trueValues[i];

        if (trueValue === desiredValue) {
            return true;
        }
    }

    return false;
}

function excludeByField(filter, data) {
    if (!filter) throw new Error('Missing value for "filter"');
    if (!data) throw new Error('Missing value for "data"');

    var field = filter[0];
    var permutations = getFieldPermutations(field, data);
    var desiredValue = filter[1];
    var trueValues = permutations.map(function(p) {
        return getDescendantProp(data, p);
    });

    for (var i = 0; i < trueValues.length; i++) {
        var trueValue = trueValues[i];

        if (trueValue === desiredValue) {
            return false;
        }
    }

    return true;
}