为什么获取Body对象只能读取一次？ [英] Why fetch Body object can be read only once?

问题描述

fetch 规格声明可读流 Body 包含 Body.bodyUsed 标志，该标志最初设置为 false 然后通过调用任何解析方法设置为 true 。

The fetch specification states that the readable stream Body contains the Body.bodyUsed flag which is initially set to false and then is set to true with a call of any parsing method.

以下是一个例子：

fetch('/some/path', (res) => {
    // res.body.bodyUsed === false
    res.json();
    // res.body.bodyUsed === true
});

如果您尝试调用类似 res.json（）的方法或 res.text（）再一次抛出异常。

If you try to call a method like res.json() or res.text() once again, an exception is thrown.

问题是：为什么要使用这种行为？为什么不允许解析那个可读的流多次？我没有找到任何解释。

The question is: why that behavior is used? Why not to allow parsing that readable stream as many times as one wants? I found no explanation of the matter.

PS。在Chrome（可能还有其他浏览器）中，该标记可以作为 res.body.locked 访问。

PS. In Chrome (and maybe other browsers), that flag is accessible as res.body.locked.

推荐答案

问题是：为什么要使用这种行为？为什么不允许解析
可读流的次数？

The question is: why that behavior is used? Why not to allow parsing that readable stream as many times as one wants?

可以读取 Response.body 不止一次使用 Response.clone（）

It is possible to read Response.body more than once by using Response.clone()

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