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metamask-extension/app/scripts/lib/freezeGlobals.js
2020-11-02 17:41:28 -06:00

38 lines
1.2 KiB
JavaScript

/**
* Freezes the Promise global and prevents its reassignment.
*/
import deepFreeze from 'deep-freeze-strict'
if (process.env.IN_TEST !== 'true' && process.env.METAMASK_ENV !== 'test') {
freeze(global, 'Promise')
}
/**
* Makes a key:value pair on a target object immutable, with limitations.
* The key cannot be reassigned or deleted, and the value is recursively frozen
* using Object.freeze.
*
* Because of JavaScript language limitations, this is does not mean that the
* value is completely immutable. It is, however, better than nothing.
*
* @param {Object} target - The target object to freeze a property on.
* @param {string} key - The key to freeze.
* @param {any} [value] - The value to freeze, if different from the existing value on the target.
* @param {boolean} [enumerable=true] - If given a value, whether the property is enumerable.
*/
function freeze(target, key, value, enumerable = true) {
const opts = {
configurable: false,
writable: false,
}
if (value === undefined) {
target[key] = deepFreeze(target[key])
} else {
opts.value = deepFreeze(value)
opts.enumerable = enumerable
}
Object.defineProperty(target, key, opts)
}