js precise calculation

var numA = 0.1; 
var numB = 0.2; 
alert( numA + numB );

/** 
 ** Division function, used to get accurate division results** Note: JavaScript's division results will have errors, which will be more obvious when dividing two floating-point numbers. This function returns a more accurate division result.
 ** Call: accdiv(arg1,arg2)
 ** Return value: the exact result of dividing arg1 by arg2 **/
function accdiv(arg1, arg2) {
    var t1 = 0, t2 = 0, r1, r2;
    try {
        t1 = arg1.toString().split(".")[1].length;
    }
    catch (e) {
    }
    try {
        t2 = arg2.toString().split(".")[1].length;
    }
    catch (e) {
    }
    with (Math) {
        r1 = Number(arg1.toString().replace(".", ""));
        r2 = Number(arg2.toString().replace(".", ""));
        return (r1 / r2) * Math.pow(10, t2 - t1);
    }
}

/**
 ** Addition function, used to get accurate addition results** Note: JavaScript addition results will have errors, which will be more obvious when adding two floating point numbers. This function returns a more accurate addition result.
 ** Call: accAdd(arg1,arg2)
 ** Return value: the exact result of arg1 plus arg2 **/

function accAdd(arg1, arg2) {
    var r1, r2, m, c;
    try {
        r1 = arg1.toString().split(".")[1].length;
    }
    catch (e) {
        r1 = 0;
    }
    try {
        r2 = arg2.toString().split(".")[1].length;
    }
    catch (e) {
        r2 = 0;
    }
    c = Math.abs(r1 - r2);
    m = Math.pow(10, Math.max(r1, r2));
    if (c > 0) {
        var cm = Math.pow(10, c);
        if (r1 > r2) {
            arg1 = Number(arg1.toString().replace(".", ""));
            arg2 = Number(arg2.toString().replace(".", "")) * cm;
        } else {
            arg1 = Number(arg1.toString().replace(".", "")) * cm;
            arg2 = Number(arg2.toString().replace(".", ""));
        }
    } else {
        arg1 = Number(arg1.toString().replace(".", ""));
        arg2 = Number(arg2.toString().replace(".", ""));
    }
    return (arg1 + arg2) / m;
}

/**
 ** Multiplication function, used to get accurate multiplication results** Note: JavaScript's multiplication results will have errors, which will be more obvious when multiplying two floating-point numbers. This function returns a more accurate multiplication result.
 ** Call: accMul(arg1,arg2)
 ** Return value: the exact result of multiplying arg1 by arg2 **/
function accMul(arg1, arg2) {
    var m = 0, s1 = arg1.toString(), s2 = arg2.toString();
    try {
        m += s1.split(".")[1].length;
    }
    catch (e) {
    }
    try {
        m += s2.split(".")[1].length;
    }
    catch (e) {
    }
    return Number(s1.replace(".", "")) * Number(s2.replace(".", "")) / Math.pow(10, m);
}