print_r(), JavaScript Edition

5,821 Recognized Expert Expert

Looking for a print_r() for JavaScript? Look no further! Finally, a decent way to figure out what's in that mysterious Array or Object!

Note that this version of print_r() relies on (included) getType(), which is designed to be a browser-independent way of detecting basic types in JavaScript (unfortunately, the $object.constru ctor.match() trick doesn't work in Safari nor IE).

Special thanks to the following TSDN members whose help was invaluable and greatly appreciated during the development of this procedure:

gits
iam_clint
volectricity
Purple

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<html>

    <head>

        <script type="text/javascript">

/**

*   getType

*

*   Use this when typeof returns 'Object'.

*

*   @param mixed $obj The object to investigrate.

*

*   @return string The object's constructor.

*

*   @author Josh Zerin, Life Blue Media (http://www.lifeblue.com/)

*   @author Special thanks to:

*       - gits

*       - iam_clint

*       - volectricity

*       - Purple

*   http://www.thescripts.com/

*/

function getType($obj)

{

    /***************

    *

    *   Two special cases:  undefined and null.

    */

    if( typeof $obj == 'undefined' )

    {

        return 'undefined';

    }
 
    if($obj === null)

    {

        return 'null';

    }
 
    /***************

    *

    *   Run through the standard constructors.

    */

    switch($obj.constructor)

    {

        case Array:

            return 'Array';

        case Boolean:

            return 'Boolean';

        case Date:

            return 'Date';

        case Error:

            return 'Error';

        case Function:

            return 'Function';

        case Number:

            return 'Number';

        case RegExp:

            return 'RegExp';

        case String:

            return 'String';

        default:
 
            /***************

            *

            *   HTML Elements will have a nodeType property.  It is unlikely, though possible, that other objects will.

            */

            if( typeof($obj.nodeType) != 'undefined' )

            {

                return 'HTML ' + $obj.nodeName.toUpperCase() + ' Element';

            }
 
            /***************

            *

            *   If it's not an HTML Element, it might be an Event.

            */

            if($obj.toString)

            {

                if($obj.toString().match('Event'))

                {

                    return 'Event';

                }

            }
 
            /***************

            *

            *   I give up.

            */

            return 'Object';

    }

}
 
/**

*

*   print_r

*

*   Similar to the PHP function of the same name, except it always returns its output (I never liked that about PHP's print_r()).

*

*   @param mixed $content The variable you're trying to print_r.  Generally an object or array.

*

*   @param bool $htmlEncode How to format the output:

*       - true:     Use <br /> for line breaks, and &nbsp; for tabs.

*       - false:    Use \n for line breaks and \t for tabs.

*

*   @param string $basePrefix The base prefix that will be appended to all lines of output.  Very useful if you need your debug output to all line up (and something that REALLY bugs me about PHP's print_r()!).

*

*   @param string $_prefix (internal)

*

*   @return string A print_r()'ed string, similar in format to the PHP function of the same name (but with a few enhancements ~_^).

*

*   @author Josh Zerin, Life Blue Media (http://www.lifeblue.com/)

*   @author Special thanks to:

*       - gits

*       - iam_clint

*       - volectricity

*       - Purple

*   http://www.thescripts.com/

*/

function print_r($content, $htmlEncode, $basePrefix, $_prefix)

{

    /***************

    *

    *   $_prefix must be a string.

    */

    if( ! $_prefix )

    {

        $_prefix = '';

    }
 
    /***************

    *

    *   Set the $basePrefix if not already set.

    */

    if( ! $basePrefix )

    {

        $basePrefix =

        (

            // If $_prefix is defined, we'll just use that.

            $_prefix

                ? $_prefix

                :

                (

                    // Otherwise, use a default.

                    $htmlEncode

                        ? '&nbsp;&nbsp;&nbsp;&nbsp;'

                        : '\t'

                )

        );

    }
 
    /***************

    *

    *   How do we display newlines?

    */

    var $newLine = ($htmlEncode ? '<br />' : '') + '\n';
 
    /***************

    *

    *   Init output string.

    */

    var $retVal = '';
 
    /****************

    *

    *   We don't need to redundantly output certain types (the 'value' of null & undefined are self-explanatory, and we auto-output the type of Array & Object, so we don't want to do it twice).

    */

    var $blacklistDisplayType =

    {

        'null':         true,

        'Array':        true,

        'Object':       true,

        'undefined':    true

    }
 
    /***************

    *

    *   Begin processing $content.

    */

    var $myType = getType($content);

    var $subType = '';
 
    /***************

    *

    *   And off we go!

    */

    if( $myType == 'Array' )

    {

        // E.g., "Array:\n\t(\n"

        $retVal += $myType + ':' + $newLine + $_prefix + '(' + $newLine;
 
        /***************

        *

        *   Save the closing format before we go modifying $_prefix.

        */

        var $close = $_prefix + ')' + $newLine;
 
        /***************

        *

        *   $basePrefix is only for *child* elements of the array.

        */

        $_prefix += $basePrefix;
 
        /***************

        *

        *   for...in not useful on Arrays, since that will also return member functions.

        */

        for( var $i = 0; $i < $content.length; ++$i )

        {

            var $innerType = getType($content[$i]);
 
            // E.g., "\t\t0 => (Number) "

            $retVal += $_prefix + $i + ' => ' +

            (

                /***************

                *

                *   Should we display the type of the child element?

                */

                $blacklistDisplayType[$innerType]

                    ? ''

                    : ' (' + getType($content[$i]) + ')'

            ) + ' ';
 
            /***************

            *

            *   If the child element has children of its own, recursively process them.

            */

            if(($innerType == 'Array') || ($innerType == 'Object'))

            {

                $retVal +=

                    print_r

                    (

                        $content[$i],

                        $htmlEncode,

                        $basePrefix,

                        $_prefix

                    );

            }

            else

            {

                $retVal += $content[$i] + $newLine;

            }

        }
 
        // E.g., "\t)\n"

        $retVal += $close;

    }

    else if( $myType == 'Object' )

    {

        $retVal += $myType + ':' + $newLine + $_prefix + '(' + $newLine;

        var $close = $_prefix + ')' + $newLine;

        $_prefix += $basePrefix;
 
        /***************

        *

        *   for not useful on Objects, since they generally have no length property.

        */

        for( $i in $content )

        {

            var $innerType = getType($content[$i]);

            $retVal += $_prefix + $i + ' => ' +

            (

                $blacklistDisplayType[$innerType]

                    ? ''

                    : ' (' + getType($content[$i]) + ')'

            ) + ' ';
 
            if( ($innerType == 'Array') || ($innerType == 'Object') )

            {

                $retVal +=

                    print_r

                    (

                        $content[$i],

                        $htmlEncode,

                        $basePrefix,

                        $_prefix

                    );

            }

            else

            {

                $retVal += $content[$i] + $newLine;

            }

        }
 
        $retVal += $close;

    }

    else

    {

        /***************

        *

        *   If it ain't an object, then it's scalar.

        */

        $retVal += $content;

    }
 
    /***************

    *

    *   And we're done!

    */

    return $retVal;

}

        </script>

    </head>
 
    <body>

        <script type="text/javascript">

        // <![CDATA[
 
            /*

                Desired output:
 
                Object:

                (

                    Array => Array:

                    (

                        0 => (Number) 0

                        1 => (String) 1

                        2 => (Number) 2.3

                        3 => (String) Four

                        4 => Object:

                        (

                            Five => (Number) 5

                        )

                    )

                    Number => (Number) 1

                    Float => (Number) 2.3

                    String => (String) Four

                    Sub => Object:

                    (

                        empty => (Boolean) false

                    )

                    null => null

                    undef => undefined

                    Element => (HTML BODY Element) [object HTMLBodyElement]

                )

            */
 
            var $theObj = {

                'Array':    [

                    0, '1', 2.3, 'Four', { 'Five': 5 }

                ],

                'Number':   1,

                'Float':    2.3,

                'String':   'Four',

                'Sub':      {

                    'empty':    false

                },

                'null':     null,

                'undef':    undefined,

                'Element':  document.getElementsByTagName('body')[0]

            };
 
            document.write(print_r($theObj, true));

        // ]]>

        </script>

    </body>

</html>

Attached Files

print_r.html.zip (2.8 KB, 327 views)

Aug 31 '07 #1

Subscribe Reply

7155

Robert Kehoe

New Member

Awesome function, works great for me! :)

Just one question, what license can the code be used under? BSD, MIT, LGPL, etc... ?

Sep 14 '10 #2

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