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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
    <script>
        
        var unique = function (str) {
            var temp = {},
                newStr = '',
                len = str.length;
            for (var i = 0; i < len; i++) {
                if (!temp[str[i]]){
                    temp[str[i]] = "abc";
                    newStr += str[i];
                }
            }
            return newStr ;
        }
        var a = "aabbcc";
        console.log (unique(a));            //结果为"abc"

                  
        
        

        
    </script>

    
</body>
</html>