console

var externalObj = {key: 'value'};

var items = {
  obj: {
    'string prop': 'string val',
    5: 10,
    nested: [[3, [5, 2]]],
    'function': function(){return true;},
    reference: externalObj
  },
  arr: [1, 2, 'hi', 'mom'],
  str: 'poppler',
  bool: true,
  inum: 5,
  fnum: 3.14159265,
  regex: /[a-zA-Z]{3}[0-9]{2}/g,
  func: function(){return false;}
};

for (var item in items) {
  console.groupCollapsed(item);
  item = items[item];

  console.log('------ .toString() ------');
  console.log(item.toString());
  console.log('------ String() ------');
  console.log(String(item));
  console.log('------ .log(item) ------');
  console.log(item);
  console.log('------ .log("string " + item)');
  console.log('string'  + item);
  console.log('------ .log("string", item)');
  console.log('string', item);
  console.log('------ .log(%s, item)');  
  console.log('%s', item);
  console.log('------ .log(%d, item)'); 
  console.log('%d', item); 
  console.log('------ .log(%i, item)');  
  console.log('%i', item);
  console.log('------ .log(%f, item)');  
  console.log('%f', item);
  console.log('------ .log(%o, item)');  
  console.log('%o', item);
  console.log('------ .log(%O, item)');
  console.log('%O', item);
  console.log('------ .dir(item)');
  console.dir(item);

  console.groupEnd();
}