twig/src/twig.tests.js

JS port of the Twig templating language.

// ## twig.tests.js
//
// This file handles expression tests. (is empty, is not defined, etc...)
module.exports = function (Twig) {
    'use strict';
    Twig.tests = {
        empty(value) {
            // Handle boolean true
            if (value === true) {
                return false;
            }

            // Handle null or undefined
            if (value === null || value === undefined) {
                return true;
            }

            // Handler numbers
            if (typeof value === 'number') {
                return false;
            } // Numbers are never "empty"

            // Handle strings and arrays
            if (value.length > 0) {
                return false;
            }

            // Handle objects
            for (const key in value) {
                if (Object.hasOwnProperty.call(value, key)) {
                    return false;
                }
            }

            return true;
        },
        odd(value) {
            return value % 2 === 1;
        },
        even(value) {
            return value % 2 === 0;
        },
        'divisible by'(value, params) {
            return value % params[0] === 0;
        },
        divisibleby(value, params) {
            console.warn('`divisibleby` is deprecated use `divisible by`');
            return Twig.tests['divisible by'](value, params);
        },
        defined(value) {
            return value !== undefined;
        },
        none(value) {
            return value === null;
        },
        null(value) {
            return this.none(value); // Alias of none
        },
        'same as'(value, params) {
            return value === params[0];
        },
        sameas(value, params) {
            console.warn('`sameas` is deprecated use `same as`');
            return Twig.tests['same as'](value, params);
        },
        iterable(value) {
            return value && (Twig.lib.is('Array', value) || Twig.lib.is('Object', value));
        }
        /*
        Constant ?
         */
    };

    Twig.test = function (test, value, params) {
        if (!Twig.tests[test]) {
            throw Twig.Error('Test ' + test + ' is not defined.');
        }

        return Twig.tests[test](value, params);
    };

    Twig.test.extend = function (test, definition) {
        Twig.tests[test] = definition;
    };

    return Twig;
};