phpjs/experimental/errorfunc/set_exception_handler.js

php.js offers community built php functions in javascript

function set_exception_handler(callback) {
  // http://kevin.vanzonneveld.net
  // +   original by: Brett Zamir (http://brett-zamir.me)
  // *     example 1: set_exception_handler(function (exceptionObj) {alert(exceptionObj.getMessage());});
  // *     returns 1: null

  var that = this, oldHandlerName = '';
  var _getFuncName = function(fn) {
    var name = (/\W*function\s+([\w\$]+)\s*\(/).exec(fn);
    if (!name) {
      return '(Anonymous)';
    }
    return name[1];
  };
  if (typeof callback === 'string') {
    callback = this.window[callback];
  }
  // BEGIN REDUNDANT
  this.php_js = this.php_js || {};
  // END REDUNDANT
  // For return
  oldHandlerName = this.php_js.exception_handler ? _getFuncName(this.php_js.exception_handler) : null;

  if (this.php_js.exception_handler) { // Fix: Any potential built-in ones (e.g., via ini) to fall back on, as the PHP manual suggests?
    this.php_js.previous_exception_handler = this.php_js.exception_handler; // usable by restore_exception_handler()
  }

  // Set callback
  this.php_js.exception_handler = callback;

  // Make available a global Exception class (see _experimental/language)
  if (!this.window.Exception) {
    this.window.Exception = function(message, code) {
      // These four are supposed to be protected (extendable, but not public)
      this.message = message || '';
      this.code = code || 0; // user defined exception code
      // Fix: Just putting something here for the next two (not PHP-style)... Can over-ride if extending, however;
      //    in Mozilla, error objects (e.g., if you're in a catch block), have these properties which might be used to
      //    add to the object after instantiation (or during instantiation if extending the exception): fileName,
      //    lineNumber, stack; actually, should use PHP Error object for these anyways if following the PHP API
      //    since it does have these properties
      //  Note that for the trace, however, in Mozilla the stack property is a string, and getTrace() needs the items
      //    parsed as an array; this might be doable by setting the exception object's trace property to
      //    "e.stack.replace(/\n$/, '').split('\n');" if 'e' is a JavaScript exception
      this.file = this.window.href.location; // source filename of exception
      this.line = 0; // source line of exception

      this.string = 'Exception'; // private string; Internal Exception name
      this.name = 'Exception';  // To fit the JavaScript Error interface, user could also add a custom name property.
      that.php_js.exception_handler(this);
    };
    this.window.Exception.prototype = {
      constructor: this.window.Exception,
      // FINAL (not supposed to extend the following 6 methods)
      getMessage: function() { // message of exception
        return this.message;
      },
      getCode: function() { // code of exception
        return this.code;
      },
      getFile: function() { // source filename
        return this.file;
      },
      getLine: function() { // source line
        return this.line;
      },
      getTrace: function() { // an array of the backtrace()
        // Todo: add trace for Mozilla, etc.
        var ret = '';
        for (var i = 0; i < this.trace.length; i++) {
          ret += '\n#' + i + ' ' + this.trace[i];
        }
        return ret.slice(1);
        // return this.trace; // should be an array (especially so that getTraceAsString() works properly)
      },
      getTraceAsString: function() { // formatted string of trace
        // Todo: add trace for Mozilla, etc.
        return this.trace.toString();
      },
      // Overrideable
      __toString: function() { // formatted string for display
        // PHP-style
        return "exception '" + this.string + "' with message '" + this.getMessage() + "' in " +
            this.getFile() + ':' + this.getLine() + '\nStack trace:\n' + this.getTraceAsString();
        // return this.name+': '+this.message; // this works also, but in JavaScript-style
      },
      // For JavaScript interface/behavior:
      toString: function() {
        return this.__toString(); // We implement on toString() to implement JavaScript Error interface
      },
      // PRIVATE FINAL METHODS
      __clone: function() {
        throw 'Fatal exception: exceptions are not clonable';
      }
    };
  }

  return oldHandlerName;
}