mattermost-redux
Version:
Common code (API client, Redux stores, logic, utility functions) for building a Mattermost client
59 lines (58 loc) • 2.41 kB
JavaScript
;
/**
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*
*/
Object.defineProperty(exports, "__esModule", { value: true });
exports.default = deepFreezeAndThrowOnMutation;
/* eslint-disable header/header */
/**
* If your application is accepting different values for the same field over
* time and is doing a diff on them, you can either (1) create a copy or
* (2) ensure that those values are not mutated behind two passes.
* This function helps you with (2) by freezing the object and throwing if
* the user subsequently modifies the value.
*
* There are two caveats with this function:
* - If the call site is not in strict mode, it will only throw when
* mutating existing fields, adding a new one
* will unfortunately fail silently :(
* - If the object is already frozen or sealed, it will not continue the
* deep traversal and will leave leaf nodes unfrozen.
*
* Freezing the object and adding the throw mechanism is expensive and will
* only be used in DEV.
*/
function deepFreezeAndThrowOnMutation(object) {
// Some objects in IE11 don't have a hasOwnProperty method so don't even bother trying to freeze them
if (typeof object !== 'object' || object === null || Object.isFrozen(object) || Object.isSealed(object)) {
return object;
}
for (const key in object) {
if (Object.hasOwn(object, key)) {
object.__defineGetter__(key, identity.bind(null, object[key])); // eslint-disable-line no-underscore-dangle
object.__defineSetter__(key, throwOnImmutableMutation.bind(null, key)); // eslint-disable-line no-underscore-dangle
}
}
Object.freeze(object);
Object.seal(object);
for (const key in object) {
if (Object.hasOwn(object, key)) {
deepFreezeAndThrowOnMutation(object[key]);
}
}
return object;
}
function throwOnImmutableMutation(key, value) {
throw Error('You attempted to set the key `' + key + '` with the value `' +
JSON.stringify(value) + '` on an object that is meant to be immutable ' +
'and has been frozen.');
}
function identity(value) {
return value;
}