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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at <http://mozilla.org/MPL/2.0/>. */
/**
* Shallow equal will consider equal:
* - exact same values (strict '===' equality)
* - distinct array instances having the exact same values in them (same number and strict equality).
* - distinct object instances having the exact same attributes and values.
*
* It will typically consider different array and object whose values
* aren't strictly equal. You may consider using "deep equality" checks for this scenario.
*/
export function shallowEqual(value, other) {
if (value === other) {
return true;
}
if (Array.isArray(value) && Array.isArray(other)) {
return arrayShallowEqual(value, other);
}
if (isObject(value) && isObject(other)) {
return objectShallowEqual(value, other);
}
return false;
}
export function arrayShallowEqual(value, other) {
// Redo this check in case we are called directly from the selectors.
if (value === other) {
return true;
}
return value.length === other.length && value.every((k, i) => k === other[i]);
}
function objectShallowEqual(value, other) {
const existingKeys = Object.keys(other);
const keys = Object.keys(value);
return (
keys.length === existingKeys.length &&
keys.every((k, i) => k === existingKeys[i]) &&
keys.every(k => value[k] === other[k])
);
}
function isObject(value) {
return typeof value === "object" && !!value;
}
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