JavaScript is Object Empty

by Slava Fomin II

JavaScript

/**
 * Returns true if specified object has no properties,
 * false otherwise.
 *
 * @param {object} object
 * @returns {boolean}
 */
function isObjectEmpty(object)
{
    if ('object' !== typeof object) {
        throw new Error('Object must be specified.');
    }
    
    if (null === object) {
        return true;
    }

    if ('undefined' !== Object.keys) {
        // Using ECMAScript 5 feature.
        return (0 === Object.keys(object).length);
    } else {
        // Using legacy compatibility mode.
        for (var key in object) {
            if (object.hasOwnProperty(key)) {
                return false;
            }
        }
        return true;
    }
}

// Simple test.

var errorsCount = 
    !isObjectEmpty({
        foo: 'foo'
    })                           ? 0 : 1
+
    !isObjectEmpty({
        foo: 'foo',
        bar: 'bar'
    })                           ? 0 : 1
+
    !isObjectEmpty({
        func: function() {}
    })                           ? 0 : 1
+
    isObjectEmpty({})            ? 0 : 1
+
    isObjectEmpty(new Object())  ? 0 : 1
+
    isObjectEmpty(null)          ? 0 : 1
;

alert(errorsCount == 0 ? 'Test OK!' : 'Test failed!');