encodeURI()

encodeURI(uri)

Returns: string · Added in vES1 · Updated March 14, 2026 · Global Functions

javascript encodeuri uri encoding url

The encodeURI() function encodes a Uniform Resource Identifier (URI) by replacing certain characters with escape sequences. It encodes all characters except those that have special meaning in URIs.

Syntax

encodeURI(uri)

Parameters

Parameter	Type	Description
`uri`	string	The complete URI to encode.

Return Value

A new encoded string.

What encodeURI() Does NOT Encode

This function preserves certain characters that have special meaning in URIs:

encodeURI("ABCabc0123-_.~");
// "ABCabc0123-_.~" - unreserved characters preserved

encodeURI("hello world");
// "hello%20world" - spaces encoded

encodeURI("a/b?c=d");
// "a/b?c=d" - slashes, question marks preserved

encodeURI("test&foo=bar");
// "test&foo=bar" - ampersand preserved

Examples

Encoding Full URLs

encodeURI("https://example.com/my page");
// "https://example.com/my%20page"

encodeURI("https://example.com/search?q=hello world");
// "https://example.com/search?q=hello%20world"

Encoding Unicode Characters

encodeURI("JavaScript教程");
// "JavaScript%E6%95%99%E7%A8%8B"

encodeURI("café");
// "caf%C3%A9"

Encoding Query String Components

When building query strings, you often need to encode individual components:

const name = "John Doe";
const query = "name=" + encodeURI(name);
// "name=John%20Doe"

When to Use encodeURI vs encodeURIComponent

Use encodeURI() when encoding a complete URI:

encodeURI("https://example.com/path");
// "https://example.com/path" - already valid URI

encodeURI("https://example.com/path name");
// "https://example.com/path%20name" - spaces encoded

Use encodeURIComponent() when encoding a URI component (like a query parameter value):

encodeURIComponent("?q=hello");
// "%3Fq%3Dhello" - encodes everything including ? and =

// Wrong for full URLs - breaks the URL structure
encodeURIComponent("https://example.com");
// "https%3A%2F%2Fexample.com" - breaks the protocol!

Common Mistakes

Encoding an Already Encoded String

// Don't double-encode
const encoded = encodeURI("hello world");
// "hello%20world"

encodeURI(encoded);
// "hello%2520world" - the % becomes %25!

Using encodeURI for User Input

// For form data that will be sent as query parameters
const userInput = document.getElementById("search").value;
const param = encodeURIComponent(userInput);
const url = "/search?q=" + param;