JavaScript Object.combine method

Classes.js

Object.combine = function (keys, values) {
    if (!keys.length || !values.length || keys.length != values.length) {
        return null;
    }

    var index = null,
        length = keys.length,
        results = {};

    for (index = 0; index < length; index++) {
        results[keys[index]] = values[index];
    }

    return results;
};

var _classes = [
    'interface-renderer-time-excluded',
    'interface-renderer-time-selected',
    'interface-renderer-time-current',
    'interface-renderer-date-previous-month',
    'interface-renderer-date-next-month',
    'interface-renderer-date-current',
    'interface-form-cropper-element',
    'interface-form-element-textbox-element',
    'interface-form-element-textbox-focussed',
    'interface-form-element-textbox-disabled',
    'interface-form-element-textbox-clicked',
    'interface-form-element-textarea-element',
    'interface-form-element-textarea-focussed',
    'interface-form-element-textarea-disabled',
    'interface-form-element-textarea-clicked',
    'interface-form-element-button-element',
    'interface-form-element-button-focussed',
    'interface-form-element-button-disabled',
    'interface-form-element-button-clicked',
    'interface-form-element-checkbox-element',
    'interface-form-element-checkbox-focussed',
    'interface-form-element-checkbox-disabled',
    'interface-form-element-checkbox-clicked',
    'interface-form-element-checkbox-checked',
    'interface-form-element-radio-element',
    'interface-form-element-radio-focussed',
    'interface-form-element-radio-disabled',
    'interface-form-element-radio-clicked',
    'interface-form-element-radio-checked'
];

Classes = Object.combine(
    Array.from(_classes),
    Array.from(_classes)
);

console.log(Classes);

Isn't this the same as _classes.associate(_classes) -- http://mootools.net/docs/core/Types/Array#Array:associate

It is very similar, except for a two small differences:

• If either array has no items, this method returns null instead of an empty object.
• If their lengths do not match, this method returns null instead of a partial set of key-value pairs (according to the incomplete array).

Currently there is no way to know if the results of values.associate(keys) returns a valid array according to these 2 conditions without further inspection - the method above can be compared to null to find this out. I also prefer this syntax over associate. :)