The encodeURI()
function encodes a Uniform Resource Identifier (URI) by replacing each instance of certain characters by one, two, three, or four escape sequences representing the UTF-8 encoding of the character (will only be four escape sequences for characters composed of two "surrogate" characters).
Syntax
encodeURI(URI)
Parameters
URI
- A complete Uniform Resource Identifier.
Return value
A new string representing the provided string encoded as a Uniform Resource Identifier (URI).
Description
Does not encode characters that have special meaning (reserved characters) for a URI. The following example shows all the parts that a URI "scheme" can possibly contain. Note how certain characters are used to signify special meaning:
http://username:password@www.example.com:80/path/to/file.php?foo=316&bar=this+has+spaces#anchor
Hence encodeURI does not encode characters that are necessary to formulate a complete URI. Also, encodeURI does not encode a few additional characters, known as "unreserved marks", which do not have a reserved purpose but are allowed in a URI "as is". (See RFC2396)
encodeURI
escapes all characters except:
N
ot Escaped: A-Z a-z 0-9 ; , / ? : @ & = + $ - _ . ! ~ * ' ( ) #
encodeURI differs from encodeURIComponent
as follows:
var set1 = ";,/?:@&=+$#"; // Reserved Characters var set2 = "-_.!~*'()"; // Unreserved Marks var set3 = "ABC abc 123"; // Alphanumeric Characters + Space console.log(encodeURI(set1)); // ;,/?:@&=+$# console.log(encodeURI(set2)); // -_.!~*'() console.log(encodeURI(set3)); // ABC%20abc%20123 (the space gets encoded as %20) console.log(encodeURIComponent(set1)); // %3B%2C%2F%3F%3A%40%26%3D%2B%24%23 console.log(encodeURIComponent(set2)); // -_.!~*'() console.log(encodeURIComponent(set3)); // ABC%20abc%20123 (the space gets encoded as %20)
Note that a URIError
will be thrown if one attempts to encode a surrogate which is not part of a high-low pair, e.g.,
// high-low pair ok console.log(encodeURIComponent('\uD800\uDFFF')); // lone high surrogate throws "URIError: malformed URI sequence" console.log(encodeURIComponent('\uD800')); // lone low surrogate throws "URIError: malformed URI sequence" console.log(encodeURIComponent('\uDFFF'));
Note that encodeURI
by itself cannot form proper HTTP GET and POST requests, such as for XMLHTTPRequests, because "&", "+", and "=" are not encoded, which are treated as special characters in GET and POST requests. encodeURIComponent
, however, does encode these characters.
Note that an URIError
will be thrown if one attempts to encode a surrogate which is not part of a high-low pair, e.g.,
// high-low pair ok console.log(encodeURI('\uD800\uDFFF')); // lone high surrogate throws "URIError: malformed URI sequence" console.log(encodeURI('\uD800')); // lone low surrogate throws "URIError: malformed URI sequence" console.log(encodeURI('\uDFFF'));
Also note that if one wishes to follow the more recent RFC3986 for URLs, which makes square brackets reserved (for IPv6) and thus not encoded when forming something which could be part of a URL (such as a host), the following code snippet may help:
function fixedEncodeURI(str) { return encodeURI(str).replace(/%5B/g, '[').replace(/%5D/g, ']'); }
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 3rd Edition (ECMA-262) | Standard | Initial definition. |
ECMAScript 5.1 (ECMA-262) The definition of 'encodeURI' in that specification. |
Standard | |
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'encodeURI' in that specification. |
Standard | |
ECMAScript Latest Draft (ECMA-262) The definition of 'encodeURI' in that specification. |
Living Standard |
Browser compatibility
Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | Yes | Yes | Yes | Yes | Yes | Yes |
Feature | Android webview | Chrome for Android | Edge mobile | Firefox for Android | IE mobile | Opera Android | iOS Safari |
---|---|---|---|---|---|---|---|
Basic support | Yes | Yes | Yes | Yes | Yes | Yes | Yes |