Untitled

My HTML CODE:

<body>
<div>
    <center>
        <form action="Javascript:void(0);"method="post" onsubmit="subm();">
            <label for="fname">First Name:</label>&emsp;
            <input type="text" id="fname" />
            <br/>
            <label for="lname">Last Name:</label>&emsp;
            <input type="text" id="lname" />
            <br/>
            <label for="uname">User Name:</label>&emsp;
            <input type="text" id="uname" />
            <br/>
            <label for="pass">Password:</label>&emsp;&ensp;&nbsp;
            <input type="text" id="pass" />
            <br/>
            <label for="dob">Date of Birth:</label>&emsp;&emsp;&nbsp;
            <input type="date" id="dob" />
            <br/>
            <label>Age:</label>&emsp;&emsp;&emsp;&emsp;&emsp;
            <input type="text" id="age" />
            <br/>
            <span>Gender:</span>&emsp;&emsp;&emsp;&emsp;&ensp;
            <input type="radio" name="gender" id="male" />
            <label for="male">Male</label>
            <input type="radio" name="gender" id="female" />
            <label for="female">Female</label>
            <br/>
            <p>For what purpose(s) you are making account?</p>
            <input type="checkbox" id="app" name="purpose" value="storingapps" />
            <label for="app">Storing Apps</label>
            <input type="checkbox" id="site" name="purpose" value="storingsites" />
            <label for="site">Storing Sites</label>
            <input type="checkbox" id="fun" name="purpose" value="fun" />
            <label for="fun">Fun</label>
            <br/>
            <input type="submit" value="Submit"  class="button" />
        </form>
    </center>
</div>

MY JS CODE:

<script>
    var labelsarray = document.getElementsByTagName("label");
    var inputsarray = document.getElementsByTagName("input");
    var array = [];
    function subm() {
        var users = {
            FirstName: inputsarray[0].value,
            LastName: inputsarray[1].value,
            UserName: inputsarray[2].value,
            Password:  inputsarray[3].value,
            DateofBirth: inputsarray[4].value,
            Age: inputsarray[5].value,
            Purpose: ""
        };
        if (inputsarray[6].checked === true) {
            users.Gender = "Male";
        }
        else if (inputsarray[7].checked === true) {
            users.Gender = "Female";
        }
        if (inputsarray[8].checked === true) {
            users.Purpose += " Storing Apps";
        }
        if (inputsarray[9].checked === true) {
            users.Purpose += " Storing Sites";
        }
        if (inputsarray[10].checked === true) {
            users.Purpose += " Fun";
        }
        array.push(users);
        for (var i=0;i<array.length;i++) {
            localStorage.setItem("User Data: ", JSON.stringify(array[i]));
        }
    }
</script>