URI (Uniform Resource Locator)

URI = URL & URN.

Since URL is so popular, sometimes, we make URI = URL.

URI format

scheme :// host:port /path ?query #fragment

• scheme: It can be http, https, ftp, file, ...

• host: It can be domain name or IP address.

• port (optional): If the port is omitted, a default port will be applied. For http, it's 80, https is 443.

• path: It starts with /.

• query: It's in key-value format, starts with ?, connects the items by &. For example, ?name=jack&age=10

• fragment: It's only used by the client. The browser won't send it to the server.

URI Encoding

URI uses ASCII code.

1. It converts non-ASCII codes or special characters into hexadecimal byte, and add % before it.

   For exemple, space is %20.

2. Use encodeURL().

   It encodes a URI by replacing each instance of certain characters by one, two, three, or four escape sequences representing the UTF-8 encoding of the character.

   const uri = 'https://mozilla.org/?x=шеллы';
    const encoded = encodeURI(uri);
    console.log(encoded);
    // expected output: "https://mozilla.org/?x=%D1%88%D0%B5%D0%BB%D0%BB%D1%8B"