Update
## Compatibility For safety, it may be a good idea to use it with default values. ```js let isUndefined = void Number, // Static type constraint does not take effect isNumberUndefined = void(Number)|undefined; // Static type constraint take effect ``` ## Pending I'm not sure if it is necessary to support multiple levels of nesting ```js class ConfigType { constructor() { void { version: Number, encodeNames: Boolean, lines: [String], filename: String, linker: undefined | { // Need support? statics: { [String]: Number }, } }; } } ``` _______________________________________________ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss