status-im
/
react-native
mirror of https://github.com/status-im/react-native.git
2
0
Fork 0
Code Issues Projects Releases Wiki Activity

Ensure that existing properties are configurable before redefining 

Summary:
`Libraries/JavaScriptAppEngine/Initialization/InitializeJavaScriptAppEngine.js` attempts to setup global variables typical in most JavaScript environments. It finds the previous property value using `Object.getOwnPropertyDescriptor` and preserves it as `original[PropertyName]` (if it existed), it then redefines the property using `Object.defineProperty`.

Properties may only be redefined if the property descriptor specifies that it is configurable ([MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/getOwnPropertyDescriptor)). Attempting to redefine an non-configurable property will result in an error: `TypeError: Cannot redefine property: [PropertyName]`.

Not all properties being setup in `InitializeJavaScriptAppEngine.js` are necessarily configurable in the target environment.
Closes https://github.com/facebook/react-native/pull/9244

Differential Revision: D3679683

fbshipit-source-id: cd3398ef2cdf38e58c58862e64b159951c2b22c2
This commit is contained in:
Cameron Hunter 2016-08-05 21:44:32 -07:00 committed by Facebook Github Bot 6
parent 12fb313e54
commit bdf5adc40b
1 changed files with 19 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
Libraries/JavaScriptAppEngine/Initialization/InitializeJavaScriptAppEngine.js
View File

@ -77,13 +77,16 @@ function defineProperty(object: Object, name: string, newValue: mixed): void {
value: object[name],
});
}
const {enumerable, writable} = descriptor || {};
Object.defineProperty(object, name, {
configurable: true,
enumerable: enumerable !== false,
writable: writable !== false,
value: newValue,
});
const {enumerable, writable, configurable} = descriptor || {};
if (!descriptor || configurable) {
Object.defineProperty(object, name, {
configurable: true,
enumerable: enumerable !== false,
writable: writable !== false,
value: newValue,
});
}
}
function defineLazyProperty<T>(
@ -98,11 +101,15 @@ function defineLazyProperty<T>(
const backupName = `original${name[0].toUpperCase()}${name.substr(1)}`;
Object.defineProperty(object, backupName, descriptor);
}
defineLazyObjectProperty(object, name, {
get: getNewValue,
enumerable: descriptor ? descriptor.enumerable !== false : true,
writable: descriptor ? descriptor.writable !== false : true,
});
const {configurable} = descriptor || {};
if (!descriptor || configurable) {
defineLazyObjectProperty(object, name, {
get: getNewValue,
enumerable: descriptor ? descriptor.enumerable !== false : true,
writable: descriptor ? descriptor.writable !== false : true,
});
}
}
function setUpErrorHandler(): void {