Percent-encoding - MDN Web Docs Glossary: Definitions of Web-related terms | MDN (original) (raw)
Percent-encoding is a mechanism to encode 8-bit characters that have specific meaning in the context of URLs. It is sometimes called URL encoding. The encoding consists of substitution: A '%' followed by the hexadecimal representation of the ASCII value of the replace character.
Special characters needing encoding are: ':', '/', '?', '#', '[', ']', '@', '!', '$', '&', "'", '(', ')', '*', '+', ',', ';', '=', as well as '%' itself. Other characters don't need to be encoded, though they could.
| Character | Encoding |
|---|---|
| ':' | %3A |
| '/' | %2F |
| '?' | %3F |
| '#' | %23 |
| '[' | %5B |
| ']' | %5D |
| '@' | %40 |
| '!' | %21 |
| '$' | %24 |
| '&' | %26 |
| "'" | %27 |
| '(' | %28 |
| ')' | %29 |
| '*' | %2A |
| '+' | %2B |
| ',' | %2C |
| ';' | %3B |
| '=' | %3D |
| '%' | %25 |
| ' ' | %20 or + |
Depending on the context, the character ' ' is translated to a '+' (like in the percent-encoding version used in an application/x-www-form-urlencoded message), or in '%20' like on URLs.
See also
- Definition of percent-encoding in Wikipedia.
- RFC 3986, section 2.1, where this encoding is defined.
- encodeURI() and encodeURIComponent() — functions to percent-encode URLs