object-for-in3.html

<!DOCTYPE HTML>
<html>

<head>
  <meta charset="utf-8">
</head>

<body>

  <script>

	"use strict";

	var salaries = {
		"Вася": 100,
		"Петя": 300,
		"Даша": 250
	};

	var max = 0;
	var maxName = "";

	for (var name in salaries) {
		if (salaries[name] > max) {
			max = salaries[name];
			maxName = name;
		}
	}

	alert( maxName || 'нет сотрудников' );

  </script>
 
</body>

</html>