53 lines
1.1 KiB
Plaintext
53 lines
1.1 KiB
Plaintext
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/**
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* Copyright (c) 2013-present, Facebook, Inc.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @providesModule getByPath
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* @flow
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* @typechecks
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*/
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'use strict';
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/**
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* Get a value from an object based on the given path
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*
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* Usage example:
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*
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* var obj = {
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* a : {
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* b : 123
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* }
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* };
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*
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* var result = getByPath(obj, ['a', 'b']); // 123
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*
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* You may also specify the path using an object with a path field
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*
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* var result = getByPath(obj, {path: ['a', 'b']}); // 123
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*
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* If the path doesn't exist undefined will be returned
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*
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* var result = getByPath(obj, ['x', 'y', 'z']); // undefined
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*/
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function getByPath(root
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/*?Object | Error*/
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: any, path: Array<string>, fallbackValue?: any): any {
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let current = root;
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for (let i = 0; i < path.length; i++) {
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const segment = path[i]; // Use 'in' to check entire prototype chain since immutable js records
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// use prototypes
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if (current && segment in current) {
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current = current[segment];
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} else {
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return fallbackValue;
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}
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}
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return current;
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}
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module.exports = getByPath;
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