ss = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_@";

function v10toX(n, m) {

    m = String(m).replace(/ /gi, "");

    if (m == "") {

        return ""

    }

    var a = ss.substr(0, 10);

    var b = a + ".";

    if (eval("m.replace(/[" + b + "]/gi,'')") != "") {

        M("请输入有效的进制数！");

        return ""

    }

    m = m.split(".");

    if (m.length > 2) {

        M("请输入有效的进制数！");

        return ""

    }

    var a = ss.substr(0, n);

    if (m.length == 1) {

        m = m[0];

        var t = "";

        while (m != 0) {

            var b = m % n;

            t = a.charAt(b) + t;

            m = (m - b) / n

        }

        return t

    } else {

        var m0 = m[0];

        var t = "";

        while (m0 != 0) {

            var b = m0 % n;

            t = a.charAt(b) + t;

            m0 = (m0 - b) / n

        }

        var cnt = 18;

        var m1 = m[1];

        m1 = parseFloat("0." + m1);

        var d = "", b = 0;

        while (m1 != 0 && cnt > 0) {

            m1 = m1 * n;

            b = parseInt(m1);

            d = d + a.charAt(b);

            m1 = m1 - b;

            cnt--

        }

        return t + "." + d

    }

}

function vXto10(n, m) {

    m = String(m).replace(/ /gi, "");

    if (m == "") {

        return ""

    }

    var a = ss.substr(0, n);

    var b = a + ".";

    if (eval("m.replace(/[" + b + "]/gi,'')") != "") {

        M("请输入有效的" + n + "进制数！");

        return ""

    }

    m = m.split(".");

    if (m.length > 2) {

        M("请输入有效的" + n + "进制数！");

        return ""

    }

    if (m.length == 1) {

        m = m[0];

        var t = 0, c = 1;

        for (var x = m.length - 1; x > -1; x--) {

            t += c * (a.indexOf(m.charAt(x)));

            c *= n

        }

        return t

    } else {

        var m0 = m[0];

        var t = 0, c = 1;

        for (var x = m0.length - 1; x > -1; x--) {

            t += c * (a.indexOf(m0.charAt(x)));

            c *= n

        }

        var m1 = m[1];

        var d = 0, c = 1 / n;

        for (var x = 0; x < m1.length; x++) {

            d += c * (a.indexOf(m1.charAt(x)));

            c /= n

        }

        return t + d

    }

}

function vXtoY(d, b, c) {

    a = vXto10(d * 1, b);

    if (a == "") {

        return ""

    }

    a = v10toX(c, a);

    return a

}

function M(b) {

    alert(b)

}

function convert(g, h, i, f) {

    var e = document.getElementById(h).value;

    var d = document.getElementById(f);

    var b = document.getElementById(g).value;

    var c = document.getElementById(i).value;

    d.value = vXtoY(b, e, c)

}

function convert_c(g, e, f, d) {

    var c = document.getElementById(e).value;

    var b = document.getElementById(d);

    b.value = vXtoY(g, c, f)

};

<div class="row">

    <span class="span strong">二　进　制：</span>

    <div class="span four xs-four">

        <input type="text" id="bin_1" alt="二进制数" title="二进制数" class="input-text" value="10011110101110110100010">

    </div>

    <span class="span strong">十　进　制：</span>

    <div class="span four xs-four">

        <input type="text" id="ten_1" alt="十进制数" title="十进制数" class="input-text" value="">

    </div>

    <button class="button primary small" type="button" onclick="convert_c(2, 'bin_1', 10, 'ten_1');">转换</button>

</div>

<div class="row">

    <span class="span strong">十　进　制：</span>

    <div class="span four xs-four">

        <input type="text" id="ten_2" alt="十进制数" title="十进制数" class="input-text" value="520.1314">

    </div>

    <span class="span strong">二　进　制：</span>

    <div class="span four xs-four">

        <input type="text" id="bin_2" alt="二进制数" title="二进制数" class="input-text" value="">

    </div>

    <button class="button primary small" type="button" onclick="convert_c(10, 'ten_2', 2, 'bin_2');">转换</button>

</div>

<div class="divider form-hr"></div>

<div class="row">

    <span class="span strong">十　进　制：</span>

    <div class="span four xs-four">

        <input type="text" id="ten_3" alt="十进制数" title="十进制数" class="input-text" value="520.1314">

    </div>

    <span class="span strong">十六进制　：</span>

    <div class="span four xs-four">

        <input type="text" id="ten_six_3" alt="十六进制数" title="十六进制数" class="input-text" value="">

    </div>

    <button class="button primary small" type="button" onclick="convert_c(10, 'ten_3', 16, 'ten_six_3');">转换</button>

</div>

<div class="row">

    <span class="span strong">十六进制　：</span>

    <div class="span four xs-four">

        <input type="text" id="ten_six_4" alt="十六进制数" title="十六进制数" class="input-text" value="4f5da2">

    </div>

    <span class="span strong">十　进　制：</span>

    <div class="span four xs-four">

        <input type="text" id="ten_4" alt="十进制数" title="十进制数" class="input-text" value="">

    </div>

    <button class="button primary small" type="button" onclick="convert_c(16, 'ten_six_4', 10, 'ten_4');">转换</button>

</div>

<div class="divider form-hr"></div>

<div class="row">

    <span class="span strong">十　进　制：</span>

    <div class="span four xs-four">

        <input type="text" id="ten_5" alt="十进制数" title="十进制数" class="input-text" value="520.1314">

    </div>

    <span class="span strong">六十四进制：</span>

    <div class="span four xs-four">

        <input type="text" id="six_four_5" alt="六十四进制数" title="六十四进制数" class="input-text" value="">

    </div>

    <button class="button primary small" type="button" onclick="convert_c(10, 'ten_5', 64, 'six_four_5');">转换</button>

</div>

<div class="row">

    <span class="span strong">六十四进制：</span>

    <div class="span four xs-four">

        <input type="text" id="six_four_6" alt="六十四进制数" title="六十四进制数" class="input-text" value="jRSy">

    </div>

    <span class="span strong">十　进　制：</span>

    <div class="span four xs-four">

        <input type="text" id="ten_6" alt="十进制数" title="十进制数" class="input-text" value="">

    </div>

    <button class="button primary small" type="button" onclick="convert_c(64, 'six_four_6', 10, 'ten_6');">转换</button>

</div>