asUrlDecoded

Module Export

text |> text

Decodes a percent-encoded URL query parameter value into text (RFC 3986).

asUrlDecoded turns percent-encoded text back into its original form, resolving each %XX escape and interpreting the resulting bytes as UTF-8. It is the inverse of asUrlEncoded.

Decoding follows RFC 3986, which means %20 becomes a space while a + is kept as a literal plus sign.

Examples

Decode a query parameter value

import { asUrlDecoded } from 'text'

from 'blue%20%26%20green%20shoes' asUrlDecoded

// Returns: 'blue & green shoes'

Reserved characters are restored

import { asUrlDecoded } from 'text'

from 'a%20b%26c%3Dd%3Fe%2Ff%23g' asUrlDecoded

// Returns: 'a b&c=d?e/f#g'

UTF-8 escapes become non-ASCII characters

import { asUrlDecoded } from 'text'

from '%C3%85ke%20p%C3%A5%20caf%C3%A9' asUrlDecoded

// Returns: 'Åke på café'

Round-tripping

import { asUrlEncoded, asUrlDecoded } from 'text'

from 'blue & green? 100% på café +1!' asUrlEncoded asUrlDecoded

// Returns: 'blue & green? 100% på café +1!'

Notes

A + is kept as a literal plus sign. If you are decoding an application/x-www-form-urlencoded payload (an HTML form body), where + means space, replace it before decoding — see below
Sequences that aren’t valid escapes, such as %zz or a trailing %, are left untouched rather than causing a runtime error
Decoding text that was never encoded is safe: text without % sequences is returned unchanged

Decoding form-urlencoded values

For form-encoded input, turn + into a space first using replace:

import { replace, asUrlDecoded } from 'text'

from 'blue+%26+green' replace(/\+/, ' ') asUrlDecoded

// Returns: 'blue & green'