Decimal Degrees to Degrees Minutes And Seconds in Javascript

Question

Im trying to write a function that takes my decimal degrees (lat or long) and converts them to DMS degrees minutes seconds. I know I am meant to times the decimal point number by 60 then it's decimal again. But am a noob. Would I split the number?

function ConvertDDToDMS(DD) {
    eg. DD =-42.4
    D= 42;
    M= 4*60;
    S= .M * 60;
    var DMS =

    return DMS //append Direction (N, S, E, W);
}

Am I on the right track?

Answer 1

function ConvertDDToDMS(D, lng){
    const M=0|(D%1)*60e7;

    return {
        dir : D<0?lng?'W':'S':lng?'E':'N',
        deg : 0|(D<0?D=-D:D),
        min : 0|M/1e7,
        sec : (0|M/1e6%1*6e4)/100
    };
}

The above gives you an object {deg:, min:, sec:, dir:} with sec truncated to two digits (e.g. 3.14) and dir being one of N, E, S, W depending on whether you set the lng (longitude) parameter to true. e.g.:

ConvertDDToDMS(-18.213, true) == {
   deg : 18,
   min : 12,
   sec : 46.79,
   dir : 'W'
}

Or if you just want the basic string:

function ConvertDDToDMS(D){
    return [0|D, 'd ', 0|(D<0?D=-D:D)%1*60, "' ", 0|D*60%1*60, '"'].join('');
}

ConvertDDToDMS(-18.213) == `-18d 12' 46"`

[edit June 2019] -- fixing an 8 year old bug that would sometimes cause the result to be 1 minute off due to floating point math when converting an exact minute, e.g. ConvertDDToDMS(4 + 20/60). Updated code still has a slight issue, but will round to 19min 59.99 sec in this case, which is fine and not fixable due to the way floating points work