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HTML

<p>Comparisons of the various answers to <a target="_blank" href="http://stackoverflow.com/q/57803">this Stack Overflow question</a>

</p>
<table>
    <tbody id="comparison-table">
        <tr id="headings">
            <th>input</th>
            <th>.toString(16)</th>
        </tr>
    </tbody>
</table>

JavaScript

var tests = [-1, 0, 2, 200, 201, 145000, 90000000];

var answers = {
    "Tod": {
        id: 697841,
        func: function (i) {
            return (i < 0 ? 0xFFFFFFFF + i + 1 : i).toString(16).toUpperCase();
        }
    },
    "Luke Smith": {
        id: 57807,
        func: function (d, padding) {
            var hex = Number(d).toString(16);
            padding = typeof (padding) === "undefined" || padding === null ? 2 : padding;
            while (hex.length < padding) {
                hex = "0" + hex;
            }
            return hex;
        }
    },
    "quartzo": {
        id: 6680530,
        func: function (i) {
            return ("0" + (Number(i).toString(16))).slice(-2).toUpperCase();
        }
    },
    "Baznr": {
        id: 13240395,
        func: function (i) {
            return (i + 0x10000).toString(16).substr(-4).toUpperCase();
        }
    },
    "Alberto": {
        id: 17106974,
        func: function (i) {
            return (i >>> 0).toString(16);
        }
    },
    "mystifeid": {
        id: 3689638,
        func: function (i) {
            var hex = Number(i).toString(16);
            return "000000".substr(0, 6 - hex.length) + hex;
        }
    },
    "korana": {
        id: 11012314,
        func: function (n) {
            if (n < 0) {
                n = 0xFFFFFFFF + n + 1;
            }
            return "0x" + ("00000000" + n.toString(16).toUpperCase()).substr(-8);
        }
    },
    "Adamarla": {
        id: 9034019,
        func: function (decimal, chars) {
            return (decimal + Math.pow(16, chars)).toString(16).slice(-chars).toUpperCase();
        }
    }
};

var headings = document.getElementById("headings");
for (var answer in answers) {
    var id = answers[answer].id;
    headings.innerHTML += "<th><a target='_blank' href='http://stackoverflow.com/a/" + id + "/2203482'>" + answer + "</th>";
}

var table = document.getElementById("comparison-table");
for (var i in tests) {
    var dec = tests[i];
  ...