113 lines
3.0 KiB
JavaScript
113 lines
3.0 KiB
JavaScript
|
/**
|
||
|
|
* @license Apache-2.0
|
||
|
|
*
|
||
|
|
* Copyright (c) 2018 The Stdlib Authors.
|
||
|
|
*
|
||
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
||
|
|
* you may not use this file except in compliance with the License.
|
||
|
|
* You may obtain a copy of the License at
|
||
|
|
*
|
||
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
||
|
|
*
|
||
|
|
* Unless required by applicable law or agreed to in writing, software
|
||
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
||
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
|
|
* See the License for the specific language governing permissions and
|
||
|
|
* limitations under the License.
|
||
|
|
*/
|
||
|
|
|
||
|
|
'use strict';
|
||
|
|
|
||
|
|
// MODULES //
|
||
|
|
|
||
|
|
var isObject = require( './../../is-object' );
|
||
|
|
var isFunction = require( './../../is-function' );
|
||
|
|
var getPrototypeOf = require( '@stdlib/utils/get-prototype-of' );
|
||
|
|
var hasOwnProp = require( './../../has-own-property' );
|
||
|
|
var nativeClass = require( '@stdlib/utils/native-class' );
|
||
|
|
|
||
|
|
|
||
|
|
// VARIABLES //
|
||
|
|
|
||
|
|
var objectPrototype = Object.prototype;
|
||
|
|
|
||
|
|
|
||
|
|
// FUNCTIONS //
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Tests that an object only has own properties.
|
||
|
|
*
|
||
|
|
* @private
|
||
|
|
* @param {Object} obj - value to test
|
||
|
|
* @returns {boolean} boolean indicating if an object only has own properties
|
||
|
|
*/
|
||
|
|
function ownProps( obj ) {
|
||
|
|
var key;
|
||
|
|
|
||
|
|
// NOTE: possibility of perf boost if key enumeration order is known (see http://stackoverflow.com/questions/18531624/isplainobject-thing).
|
||
|
|
for ( key in obj ) {
|
||
|
|
if ( !hasOwnProp( obj, key ) ) {
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
// MAIN //
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Tests if a value is a plain object.
|
||
|
|
*
|
||
|
|
* @param {*} value - value to test
|
||
|
|
* @returns {boolean} boolean indicating whether value is a plain object
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* var bool = isPlainObject( {} );
|
||
|
|
* // returns true
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* var bool = isPlainObject( null );
|
||
|
|
* // returns false
|
||
|
|
*/
|
||
|
|
function isPlainObject( value ) {
|
||
|
|
var proto;
|
||
|
|
|
||
|
|
// Screen for obvious non-objects...
|
||
|
|
if ( !isObject( value ) ) {
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
// Objects with no prototype (e.g., `Object.create( null )`) are plain...
|
||
|
|
proto = getPrototypeOf( value );
|
||
|
|
if ( !proto ) {
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
// Objects having a prototype are plain if and only if they are constructed with a global `Object` function and the prototype points to the prototype of a plain object...
|
||
|
|
return (
|
||
|
|
// Cannot have own `constructor` property:
|
||
|
|
!hasOwnProp( value, 'constructor' ) &&
|
||
|
|
|
||
|
|
// Prototype `constructor` property must be a function (see also https://bugs.jquery.com/ticket/9897 and http://stackoverflow.com/questions/18531624/isplainobject-thing):
|
||
|
|
hasOwnProp( proto, 'constructor' ) &&
|
||
|
|
isFunction( proto.constructor ) &&
|
||
|
|
nativeClass( proto.constructor ) === '[object Function]' &&
|
||
|
|
|
||
|
|
// Test for object-specific method:
|
||
|
|
hasOwnProp( proto, 'isPrototypeOf' ) &&
|
||
|
|
isFunction( proto.isPrototypeOf ) &&
|
||
|
|
|
||
|
|
(
|
||
|
|
// Test if the prototype matches the global `Object` prototype (same realm):
|
||
|
|
proto === objectPrototype ||
|
||
|
|
|
||
|
|
// Test that all properties are own properties (cross-realm; *most* likely a plain object):
|
||
|
|
ownProps( value )
|
||
|
|
)
|
||
|
|
);
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
// EXPORTS //
|
||
|
|
|
||
|
|
module.exports = isPlainObject;
|