How to Encode and Decode URLs: RFC 3986 Percent-Encoding, URLSearchParams & Polyglot Recipes

Character: 'é' (U+00E9)
UTF-8 Representation: 2 bytes -> 0xC3 0xA9
Percent-Encoded Result: "%C3%A9"

Character: '🚀' (U+1F680 Rocket Emoji)
UTF-8 Representation: 4 bytes -> 0xF0 0x9F 0x9A 0x80
Percent-Encoded Result: "%F0%9F%9A%80"

// JavaScript / TypeScript (Browser & Node.js)
const rawParam = 'hello world & CoShareX';
const encoded = encodeURIComponent(rawParam);
console.log(encoded); // "hello%20world%20%26%20CoShareX"

const decoded = decodeURIComponent(encoded);
console.log(decoded); // "hello world & CoShareX"

# Python 3
import urllib.parse

raw_param = "hello world & CoShareX"
encoded = urllib.parse.quote(raw_param, safe="")
print(encoded)  # "hello%20world%20%26%20CoShareX"

decoded = urllib.parse.unquote(encoded)
print(decoded)  # "hello world & CoShareX"

// Go (Golang)
package main

import (
	"fmt"
	"net/url"
)

func main() {
	rawParam := "hello world & CoShareX"
	encoded := url.QueryEscape(rawParam)
	fmt.Println(encoded) // "hello+world+%26+CoShareX"

	decoded, _ := url.QueryUnescape(encoded)
	fmt.Println(decoded) // "hello world & CoShareX"
}

# Linux / macOS Shell (jq or python one-liner)
echo -n "hello world & CoShareX" | jq -sRr @uri
# Output: hello%20world%20%26%20CoShareX

export function safeUrlDecode(input: string): string {
  try {
    return decodeURIComponent(input.replace(/\+/g, ' '));
  } catch (err) {
    // Falls back gracefully on malformed percent sequences like '%E0%A4'
    console.warn('Malformed URI sequence encountered, returning raw input:', err);
    return input;
  }
}