url - 为什么 '%20' 在 URL 中用作空格的起源

Question

我很想知道为什么 '%20' 被用作 URL 中的空格，特别是为什么使用 %20 以及为什么我们甚至首先需要它。

Answer 1

它叫做 percent encoding .某些字符不能在 URI 中(例如 # ，因为它表示 URL 片段)，因此它们用可以是的字符表示( # 变成 %23 )

这是同一篇文章的摘录:

When a character from the reserved set (a "reserved character") has special meaning (a "reserved purpose") in a certain context, and a URI scheme says that it is necessary to use that character for some other purpose, then the character must be percent-encoded. Percent-encoding a reserved character involves converting the character to its corresponding byte value in ASCII and then representing that value as a pair of hexadecimal digits. The digits, preceded by a percent sign ("%") which is used as an escape character, are then used in the URI in place of the reserved character. (For a non-ASCII character, it is typically converted to its byte sequence in UTF-8, and then each byte value is represented as above.)

空格字符的字符代码是 32 :

> ' '.charCodeAt(0)
32

这是 20在 base-16 中:

> ' '.charCodeAt(0).toString(16)
"20"

在它前面加上一个百分号，你会得到 %20 .