Parse Date

toDate.ts

/**
 * Tries to return a valid date or null. It can parse (valid) date strings as well as numbers.
 * @param date a valid date or null
 */
/**
 * Tries to return a valid date or null. It can parse (valid) date strings as well as numbers.
 *
 * @param val
 * @param defaultValue
 * @returns {any}
 */
export function toDateOrNull(val: any): Date {
    return toDate(val, null);
}

function toDate(val: any, defaultValue: any = null): Date|null {
    if (val == null) {
        return defaultValue;
    }
    if (typeof val === 'boolean') {
        return defaultValue;
    }
    if (Array.isArray(val)) {
        return defaultValue;
    }
    let date: Date = null;
    if (val instanceof Date) {
        date = val;
    } else {
        date = new Date(val);
    }
    // see: https://stackoverflow.com/questions/1353684/detecting-an-invalid-date-date-instance-in-javascript
    if (isNaN(date.getTime())) {
        return defaultValue;
    }
    return date;
}

export function toDateOrNow(val: any): Date {
    let date = toDate(val, null);
    if (date == null) {
        date = new Date();
    }
    return date;
}

toDate.utest.ts

import { toDateOrNow, toDateOrNull } from './toDate';
import { assert } from 'chai';

describe('toDate module', function() {
    describe('toDateOrNull', function() {
        it('should return null on null', function() {
            assert.isNull(toDateOrNull(null));
        });
        it('should return null on undefined', function() {
            assert.isNull(toDateOrNull(undefined));
        });
        it('should return null on empty string', function() {
            assert.isNull(toDateOrNull(''));
        });
        it('should return null on invalid string', function() {
            assert.isNull(toDateOrNull('xxxx'));
        });
        it('should return null on boolean', function() {
            assert.isNull(toDateOrNull(true));
            assert.isNull(toDateOrNull(false));
        });
        it('should return null on array', function() {
            assert.isNull(toDateOrNull([]));
            assert.isNull(toDateOrNull([1, 2]));
            assert.isNull(toDateOrNull([new Date()]));
        });
        it('should return null on object', function() {
            assert.isNull(toDateOrNull({}));
            assert.isNull(toDateOrNull({ date: new Date() }));
        });
        it('should return date on number', function() {
            assert.equal(1, toDateOrNull(1).getTime());
            assert.equal(20000, toDateOrNull(20000).getTime());
        });
        it('should return same valid date', function() {
            const date = new Date();
            assert(date === toDateOrNull(date));
        });
        it('should return null valid date', function() {
            assert.isNull(toDateOrNull(new Date('invalid')));
        });
        it('should return date on valid date string', function() {
            assert.equal(
                new Date('2017-08-08T21:16:03.484Z').getTime(),
                toDateOrNull('2017-08-08T21:16:03.484Z').getTime()
            );
        });
    });
    describe('toDateOrNow', function() {
        function isNow(date: Date) {
            // let's define now as with a 1 second epsilon
            assert(Math.abs(date.getTime() - Date.now()) < 1000);
        }
        it('should return now on null', function() {
            isNow(toDateOrNow(null));
        });
        it('should return now on undefined', function() {
            isNow(toDateOrNow(undefined));
        });
        it('should return now on empty string', function() {
            isNow(toDateOrNow(''));
        });
        it('should return now on invalid string', function() {
            isNow(toDateOrNow('xxxx'));
        });
        it('should return now on boolean', function() {
            isNow(toDateOrNow(true));
            isNow(toDateOrNow(false));
        });
        it('should return now on array', function() {
            isNow(toDateOrNow([]));
            isNow(toDateOrNow([1, 2]));
            isNow(toDateOrNow([new Date()]));
        });
        it('should return now on object', function() {
            isNow(toDateOrNow({}));
            isNow(toDateOrNow({ date: new Date() }));
        });
        it('should return date on number', function() {
            assert.equal(1, toDateOrNow(1).getTime());
            assert.equal(20000, toDateOrNow(20000).getTime());
        });
        it('should return same valid date', function() {
            const date = new Date();
            assert(date === toDateOrNow(date));
        });
        it('should return now valid date', function() {
            isNow(toDateOrNow(new Date('invalid')));
        });
        it('should return date on valid date string', function() {
            assert.equal(
                new Date('2017-08-08T21:16:03.484Z').getTime(),
                toDateOrNow('2017-08-08T21:16:03.484Z').getTime()
            );
        });
    });
});