问题

以下代码

let num01 = Buffer.from(Number(1).toString(16), "hex");
console.log(num01);

let num02 = Buffer.from("02", "hex");
console.log(num02);

let num16 = Buffer.from(Number(16).toString(16), "hex");
console.log(num16);

产生以下输出：

<Buffer 01> // 如何修复这个输出为 0x01？
<Buffer 02>
<Buffer 10>

如果我输入一个小于 16 的十进制数字，上述代码的第一行无法创建带有任何值的缓冲区。如果我使用带有前导零的 `Buffer.from("02", "hex");`，那么它可以正常工作。我该如何修改第一行，以便它能够接受小于 16 的十进制数字并创建适当的缓冲区呢？

<details>
<summary>英文:</summary>

The following code

let num01 = Buffer.from(Number(1).toString(16), "hex");
console.log(num01);

let num02 = Buffer.from("02", "hex");
console.log(num02);

let num16 = Buffer.from(Number(16).toString(16), "hex");
console.log(num16);

gives the following output:

<Buffer > // how to fix this into 0x01?
<Buffer 02>
<Buffer 10>

If I input a decimal number smaller than 16, line one of the code above fails to create a buffer with any values. If I do `Buffer.from("02", "hex");` with a leading zero, then it works fine. How can I modify line one so that it will accept decimal numbers smaller than 16 a create appropriate buffers. 

</details>


# 答案1
**得分**: 1

根据[Buffer文档][1]，"解码不仅由十六进制字符组成的字符串时，可能会发生数据截断。"

当您创建`num01`时，提供的字符串是"1"，它没有正确的十六进制编码（字符数量不是偶数），因此被截断为空。

要将参数转换为具有偶数字符的字符串，您可以使用[padStart方法][2]来用零进行填充：

```javascript
let num01 = Buffer.from(Number(1).toString(16).padStart(2, "0"), "hex");

或者处理具有任意位数的数字：

let value = Number(1).toString(16);
let num01 = Buffer.from(value.length % 2 ? "0" + value : value, "hex");

let num01 = Buffer.from(Number(1).toString(16).padStart(2, "0"), "hex");

let value = Number(1).toString(16);
let num01 = Buffer.from(value.length % 2 ? "0" + value : value, "hex");