86 lines
2.5 KiB
JavaScript
86 lines
2.5 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 MAX_SAFE_INTEGER = require( '@stdlib/constants/float64/max-safe-integer' );
|
|
var isPositiveInteger = require( '@stdlib/assert/is-positive-integer' ).isPrimitive;
|
|
var getOwnPropertyDescriptor = require( './../../property-descriptor' );
|
|
var getPrototypeOf = require( './../../get-prototype-of' );
|
|
|
|
|
|
// MAIN //
|
|
|
|
/**
|
|
* Returns a property descriptor for an object's inherited property.
|
|
*
|
|
* ## Notes
|
|
*
|
|
* - In contrast to the built-in `Object.getOwnPropertyDescriptor()`, this function returns `null` if provided `undefined` or `null`, rather than throwing an error.
|
|
* - In contrast to the built-in `Object.getOwnPropertyDescriptor()`, this function returns `null` if an object does not have an inherited provided property, rather than `undefined`.
|
|
*
|
|
* @private
|
|
* @param {*} value - input object
|
|
* @param {(string|symbol)} property - property
|
|
* @param {PositiveInteger} [level] - inheritance level
|
|
* @throws {TypeError} third argument must be a positive integer
|
|
* @returns {(Object|null)} property descriptor or null
|
|
*
|
|
* @example
|
|
* var desc = inheritedPropertyDescriptor( {}, 'toString' );
|
|
* // returns {...}
|
|
*/
|
|
function inheritedPropertyDescriptor( value, property, level ) { // eslint-disable-line id-length
|
|
var desc;
|
|
var obj;
|
|
var N;
|
|
var n;
|
|
if ( arguments.length > 2 ) {
|
|
if ( !isPositiveInteger( level ) ) {
|
|
throw new TypeError( 'invalid argument. Third argument must be a positive integer. Value: `' + level + '`.' );
|
|
}
|
|
N = level;
|
|
} else {
|
|
N = MAX_SAFE_INTEGER;
|
|
}
|
|
if ( value === null || value === void 0 ) {
|
|
return null;
|
|
}
|
|
// Get the value's prototype:
|
|
obj = getPrototypeOf( value );
|
|
|
|
// Walk the prototype chain in search of a specified property...
|
|
n = 1;
|
|
while ( obj && n <= N ) {
|
|
desc = getOwnPropertyDescriptor( obj, property );
|
|
if ( desc ) {
|
|
return desc;
|
|
}
|
|
obj = getPrototypeOf( obj );
|
|
n += 1;
|
|
}
|
|
return null;
|
|
}
|
|
|
|
|
|
// EXPORTS //
|
|
|
|
module.exports = inheritedPropertyDescriptor;
|