Common useful accessories for javascript

min.accessories.js

//Some functions where taken from Jistin Windle's sketch.js at https://github.com/soulwire/sketch.js

// Modulus with support for negative integers
Mod = function(current, limit) {
    return ( (current % limit) + limit ) % limit;
};

function isArray( object ) {
  
  return Object.prototype.toString.call( object ) == '[object Array]';
}

function isFunction( object ) {
  
  return typeof object == 'function';
}

function isNumber( object ) {
  
  return typeof object == 'number';
}

function isString( object ) {
  
  return typeof object == 'string';
}

function extend( target, source, overwrite ) {
  
  for ( var key in source )
    if ( overwrite || !( key in target ) )
      target[ key ] = source[ key ];
      
  return target;
}

function proxy( method, context ) {
  
  return function() {
    method.apply(context, arguments);
  }
}

function clone( target ) {
  
  var object = {};
  for ( var key in target ) {
    // not sure why is not using hasOwnProperty
    if ( isFunction( target[ key ] ) )
      object[ key ] = proxy( target[ key ], target);
    else
      object[ key ] = target[ key ];
  }
  return object;
}