javascript difference - When are you supposed to use escape instead of encodeURI / encodeURIComponent?

between and (12)

For the purpose of encoding javascript has given three inbuilt functions -

  1. escape() - does not encode @*/+ This method is deprecated after the ECMA 3 so it should be avoided.

  2. encodeURI() - does not encode [email protected]#$&*()=:/,;?+' It assumes that the URI is a complete URI, so does not encode reserved characters that have special meaning in the URI. This method is used when the intent is to convert the complete URL instead of some special segment of URL. Example - encodeURI(''); will give -

  3. encodeURIComponent() -does not encode - _ . ! ~ * ' ( ) This function encodes a Uniform Resource Identifier (URI) component by replacing each instance of certain characters by one, two, three, or four escape sequences representing the UTF-8 encoding of the character. This method should be used to convert a component of URL. For instance some user input needs to be appended Example - encodeURI(''); will give -

All this encoding is performed in UTF 8 i.e the characters will be converted in UTF-8 format.

encodeURIComponent differ from encodeURI in that it encode reserved characters and Number sign # of encodeURI

When encoding a query string to be sent to a web server - when do you use escape() and when do you use encodeURI() or encodeURIComponent():

Use escape:

escape("% +&=");


use encodeURI() / encodeURIComponent()



encodeURI() - the escape() function is for javascript escaping, not HTTP.

encodeURIComponent doesn't encode -_.!~*'(), causing problem in posting data to php in xml string.

For example:
<xml><text x="100" y="150" value="It's a value with single quote" /> </xml>

General escape with encodeURI

You can see, single quote is not encoded. To resolve issue I created two functions to solve issue in my project, for Encoding URL:

function encodeData(s:String):String{
    return encodeURIComponent(s).replace(/\-/g, "%2D").replace(/\_/g, "%5F").replace(/\./g, "%2E").replace(/\!/g, "%21").replace(/\~/g, "%7E").replace(/\*/g, "%2A").replace(/\'/g, "%27").replace(/\(/g, "%28").replace(/\)/g, "%29");

For Decoding URL:

function decodeData(s:String):String{
        return decodeURIComponent(s.replace(/\%2D/g, "-").replace(/\%5F/g, "_").replace(/\%2E/g, ".").replace(/\%21/g, "!").replace(/\%7E/g, "~").replace(/\%2A/g, "*").replace(/\%27/g, "'").replace(/\%28/g, "(").replace(/\%29/g, ")"));
    }catch (e:Error) {
    return "";

Also remember that they all encode different sets of characters, and select the one you need appropriately. encodeURI() encodes fewer characters than encodeURIComponent(), which encodes fewer (and also different, to dannyp's point) characters than escape().

The accepted answer is good. To extend on the last part:

Note that encodeURIComponent does not escape the ' character. A common bug is to use it to create html attributes such as href='MyUrl', which could suffer an injection bug. If you are constructing html from strings, either use " instead of ' for attribute quotes, or add an extra layer of encoding (' can be encoded as %27).

If you want to be on the safe side, percent encoding unreserved characters should be encoded as well.

You can use this method to escape them (source Mozilla)

function fixedEncodeURIComponent(str) {
  return encodeURIComponent(str).replace(/[!'()*]/g, function(c) {
    return '%' + c.charCodeAt(0).toString(16);

// fixedEncodeURIComponent("'") --> "%27"

I found this article enlightening : Javascript Madness: Query String Parsing

I found it when I was trying to undersand why decodeURIComponent was not decoding '+' correctly. Here is an extract:

String:                         "A + B"
Expected Query String Encoding: "A+%2B+B"
escape("A + B") =               "A%20+%20B"     Wrong!
encodeURI("A + B") =            "A%20+%20B"     Wrong!
encodeURIComponent("A + B") =   "A%20%2B%20B"   Acceptable, but strange

Encoded String:                 "A+%2B+B"
Expected Decoding:              "A + B"
unescape("A+%2B+B") =           "A+++B"       Wrong!
decodeURI("A+%2B+B") =          "A+++B"       Wrong!
decodeURIComponent("A+%2B+B") = "A+++B"       Wrong!

The difference between encodeURI() and encodeURIComponent() are exactly 11 characters encoded by encodeURIComponent but not by encodeURI:

I generated this table easily with console.table in Google Chrome with this code:

var arr = [];
for(var i=0;i<256;i++) {
  var char=String.fromCharCode(i);
  if(encodeURI(char)!==encodeURIComponent(char)) {

Small comparison table Java vs. JavaScript vs. PHP.

1. Java URLEncoder.encode (using UTF8 charset)
2. JavaScript encodeURIComponent
3. JavaScript escape
4. PHP urlencode
5. PHP rawurlencode

char   JAVA JavaScript --PHP---
[ ]     +    %20  %20  +    %20
[!]     %21  !    %21  %21  %21
[*]     *    *    *    %2A  %2A
[']     %27  '    %27  %27  %27 
[(]     %28  (    %28  %28  %28
[)]     %29  )    %29  %29  %29
[;]     %3B  %3B  %3B  %3B  %3B
[:]     %3A  %3A  %3A  %3A  %3A
[@]     %40  %40  @    %40  %40
[&]     %26  %26  %26  %26  %26
[=]     %3D  %3D  %3D  %3D  %3D
[+]     %2B  %2B  +    %2B  %2B
[$]     %24  %24  %24  %24  %24
[,]     %2C  %2C  %2C  %2C  %2C
[/]     %2F  %2F  /    %2F  %2F
[?]     %3F  %3F  %3F  %3F  %3F
[#]     %23  %23  %23  %23  %23
[[]     %5B  %5B  %5B  %5B  %5B
[]]     %5D  %5D  %5D  %5D  %5D
[~]     %7E  ~    %7E  %7E  ~
[-]     -    -    -    -    -
[_]     _    _    _    _    _
[%]     %25  %25  %25  %25  %25
[\]     %5C  %5C  %5C  %5C  %5C
char  -JAVA-  --JavaScript--  -----PHP------
[ä]   %C3%A4  %C3%A4  %E4     %C3%A4  %C3%A4
[ф]   %D1%84  %D1%84  %u0444  %D1%84  %D1%84

Modern rewrite of @johann-echavarria's answer:

        .map((ignore, i) => String.fromCharCode(i))
            (char) =>
                encodeURI(char) !== encodeURIComponent(char)
                    ? {
                          character: char,
                          encodeURI: encodeURI(char),
                          encodeURIComponent: encodeURIComponent(char)
                    : false

Or if you can use a table, replace console.log with console.table (for the prettier output).


Don't use it! escape() is defined in section B.2.1.2 escape and the introduction text of Annex B says:

... All of the language features and behaviours specified in this annex have one or more undesirable characteristics and in the absence of legacy usage would be removed from this specification. ...
... Programmers should not use or assume the existence of these features and behaviours when writing new ECMAScript code....


Special characters are encoded with the exception of: @*_+-./

The hexadecimal form for characters, whose code unit value is 0xFF or less, is a two-digit escape sequence: %xx.

For characters with a greater code unit, the four-digit format %uxxxx is used. This is not allowed within a query string (as defined in RFC3986):

query       = *( pchar / "/" / "?" )
pchar         = unreserved / pct-encoded / sub-delims / ":" / "@"
unreserved    = ALPHA / DIGIT / "-" / "." / "_" / "~"
pct-encoded   = "%" HEXDIG HEXDIG
sub-delims    = "!" / "$" / "&" / "'" / "(" / ")"
              / "*" / "+" / "," / ";" / "="

A percent sign is only allowed if it is directly followed by two hexdigits, percent followed by u is not allowed.


Use encodeURI when you want a working URL. Make this call:

encodeURI(" file with spaces.html")

to get:

Don't call encodeURIComponent since it would destroy the URL and return


Use encodeURIComponent when you want to encode the value of a URL parameter.

var p1 = encodeURIComponent("")

Then you may create the URL you need:

var url = "" + p1 + "&param2=99";

And you will get this complete URL:

Note that encodeURIComponent does not escape the ' character. A common bug is to use it to create html attributes such as href='MyUrl', which could suffer an injection bug. If you are constructing html from strings, either use " instead of ' for attribute quotes, or add an extra layer of encoding (' can be encoded as %27).

For more information on this type of encoding you can check:

I recommend not to use one of those methods as is. Write your own function which does the right thing.

MDN has given a good example on url encoding shown below.

var fileName = 'my file(2).txt';
var header = "Content-Disposition: attachment; filename*=UTF-8''" + encodeRFC5987ValueChars(fileName);

// logs "Content-Disposition: attachment; filename*=UTF-8''my%20file%282%29.txt"

function encodeRFC5987ValueChars (str) {
    return encodeURIComponent(str).
        // Note that although RFC3986 reserves "!", RFC5987 does not,
        // so we do not need to escape it
        replace(/['()]/g, escape). // i.e., %27 %28 %29
        replace(/\*/g, '%2A').
            // The following are not required for percent-encoding per RFC5987, 
            //  so we can allow for a little better readability over the wire: |`^
            replace(/%(?:7C|60|5E)/g, unescape);

This script helped me alot. Later on, though, I found out that it messed with the media upload in my posts perhaps because it was calling the media uploader scripts twice. I solved it by adding

if( $hook != 'widgets.php' ) 

Like this:

// queue up the necessary js
function hrw_enqueue($hook) {

if( $hook != 'widgets.php' ) 

  // I also changed the path, since I was using it directly from my theme and not as a plugin
  wp_enqueue_script('hrw', get_template_directory_uri() . '/js/script.js', null, null, true);
add_action('admin_enqueue_scripts', 'hrw_enqueue');

That way the widget calls the uploader script only in the widgets' page and not in the entire admin.

javascript encoding query-string