[英]Typescript es6 modules re-export mutable variable binding
I am trying to re-export a variable using es6 module syntax, then change it and see the change reflected in the final import. 我正在尝试使用es6模块语法重新导出变量,然后对其进行更改并在最终导入中看到更改。 But it is not working as expected.
但是它没有按预期工作。 See the example below:
请参阅以下示例:
a.ts a.ts
export var a = 1;
export function changeA() { a = 2; }
b.ts b.ts
export * from './a';
c.ts c.ts
import { a, changeA } from './b';
console.log(a); // 1
changeA();
console.log(a); // Expected 2 but get 1
tsconfig.json tsconfig.json
{
"compilerOptions": {
"target": "es5",
"module": "commonjs",
"outDir": "out"
}
}
Result of run: 运行结果:
$ node out/c.js
1
1
I expect the final console.log to print 2 in order to reflect the update but it does not. 我希望最终的console.log打印2以反映更新,但事实并非如此。 However, if I compile the same example with babel it works.
但是,如果我使用babel编译相同的示例,则它可以工作。 Does re-exporting mutable variable bindings not work with typescript at all or am I just doing something wrong?
重新导出可变变量绑定是否完全不适用于Typescript,还是我做错了什么?
It is because b.ts
: 这是因为
b.ts
:
export * from './a';
transpiles to 转换为
function __export(m) {
for (var p in m) if (!exports.hasOwnProperty(p)) exports[p] = m[p];
}
__export(require('./a'));
and the value of variable a
is copied and not referenced. 并且变量
a
的值被复制而不被引用。
You can work it around this way: 您可以通过以下方式解决它:
a.ts : a.ts :
export var a = 1;
export var deeper = {
a: 1
};
export function changeA() {
a = 2;
deeper.a = 2;
}
b.ts : b.ts :
export * from './a';
c.ts : c.ts :
import { a, deeper, changeA } from './b';
console.log(a); // 1
changeA();
console.log(a); // Expected 2 but get 1
console.log(deeper.a); // prints 2 as expected
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