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

Question

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()

Answer 1

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

Answer 2

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 ~!@#$&*()=:/,;?+' 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('http://stackoverflow.com'); will give - http://stackoverflow.com

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 - encodeURIComponent('http://stackoverflow.com'); will give - http%3A%2F%2Fstackoverflow.com

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

Answer 3

Just try encodeURI() and encodeURIComponent() yourself...

console.log(encodeURIComponent('@#$%^&*'));

Input: @#$%^&*. Output: %40%23%24%25%5E%26*. So, wait, what happened to *? Why wasn't this converted? It could definitely cause problems if you tried to do linux command "$string". TLDR: You actually want fixedEncodeURIComponent() and fixedEncodeURI(). Long-story...

When to use encodeURI()? Never. encodeURI() fails to adhere to RFC3986 with regard to bracket-encoding. Use fixedEncodeURI(), as defined and further explained at the MDN encodeURI() Documentation...

function fixedEncodeURI(str) { return encodeURI(str).replace(/%5B/g, '[').replace(/%5D/g, ']'); }

When to use encodeURIComponent()? Never. encodeURIComponent() fails to adhere to RFC3986 with regard to encoding: !'()*. Use fixedEncodeURIComponent(), as defined and further explained at the MDN encodeURIComponent() Documentation...

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

Then you can use fixedEncodeURI() to encode a single URL piece, whereas fixedEncodeURIComponent() will encode URL pieces and connectors; or, simply, fixedEncodeURI() will not encode +@?=:#;,$& (as & and + are common URL operators), but fixedEncodeURIComponent() will.

Answer 4

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)) {
    arr.push({
      character:char,
      encodeURI:encodeURI(char),
      encodeURIComponent:encodeURIComponent(char)
    });
  }
}
console.table(arr);

Answer 5

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);

console.log(header); 
// 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);
}

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/encodeURIComponent

Answer 6

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
%3Cxml%3E%3Ctext%20x=%22100%22%20y=%22150%22%20value=%22It's%20a%20value%20with%20single%20quote%22%20/%3E%20%3C/xml%3E

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{
    try{
        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 "";
}