Javascript PHP's print_r()

print_r.js

//-----------------------------------------------------------------------------
//
//  print_r(expression[, _return = false ])
//
//  PHP's print_r() implemented in javascript
//
//  Usage:
//      alert(print_r([111, {a: 33, b: 44}], true))
//
//  if _return is true will return string
//  else will do document.write()
//
//
//  (yes I know, I don't use semicolons)
//
//-----------------------------------------------------------------------------
function print_r(expression, _return, padding)
{
    "use strict"
    var s

    padding = padding || ""

    function dump(obj) {
        var s = ""
        var p

        s = padding + "(\n"
        for (p in obj) {
            s += padding + "    [" + p + "] => "
            s += print_r(obj[p], true, padding + "        ")
            s += "\n"
        }
        s += padding + ")\n"
        return s
    }

    if (expression === null || expression === undefined) {
        s = ""
    } else if (expression.constructor == Object) {
        s = "Object\n" + dump(expression)
    } else if (expression.constructor == Array) {
        s = "Array\n" + dump(expression)
    } else {
        s = expression.toString()
    }
    if (_return)
        return s
    document.write(s)
}

Improved with ideas from https://github.com/kvz/phpjs/blob/master/functions/var/print_r.js