Dunno if it's a bug or a feature indeed...

I have this:

class djUtilsServerFunctions extends ezjscServerFunctions
{
    public static function ezjscore($args)
    {
        return "0";
    }

in order to call http://www.domain.com/ezjscore/call/myextension::ezjscore

It should return 0 as a plain text, but I see nothing, however, if I do "return '1'", then I'll see 1 in my page

It comes from the static function: ezjscAjaxContent::textEncode that performs some filtering:

    /**
     * Encodes mixed value to string or comma seperated list of strings
     *
     * @param mixed $mix
     * @return string
     */
    public static function textEncode( $mix )
    {
        print_r($mix);
        if ( is_array( $mix ) )
            return implode(',', array_map( array('ezjscAjaxContent', 'textEncode'), array_filter( $mix ) ) );

        return $mix;
    }

Here is the result of the print_r($mix) to show my particular content:

Array
(
    [error_text] => 
    [content] => 0
)

=> the array_filter() cleans everything indeed.
Don't understand well the need for this function indeed

As I say, maybe the behavior is good and I'm wrong.
For the time being, I prefer to return OK, KO instead of 1/0, and all is fine