Flow.js 地圖不可寫嗎？

Question

/* @flow */

let m: Map<number, string>;

m = new Map();

m[1] = 'qwe';

給出這個錯誤：

7: m[1] = 'qwe';
   ^ Cannot assign `'qwe'` to `m[1]` because an index signature declaring the expected key / value type is not writable.
7: m[1] = 'qwe';
     ^ Cannot assign `'qwe'` to `m[1]` because number [1] is incompatible with `$SymbolToStringTag` [2].
References:
7: m[1] = 'qwe';
     ^ [1]
[LIB] ..//static/v0.111.0/flowlib/core.js:606:     +[key: $SymbolToStringTag]: any;
                                                          ^ [2]

你可以在這里試試

Answer 1

啊該死的，那是因為在帶有地圖的 JS 中，你不允許m[key] = value; 只有m.set(key, value) 。