Pretty Print File Name - Skrinking the filename in the middle in order to keep extension

prettyprint.js

function prettyprint(data, max) {

    var max = max || 50,
        min = 4,
        separator = '...',
        before = max * 0.618,
        nL = data.length,
        after = max - before - separator.length;

    if (after < min) {
        after = min;
    }

    if (nL > max) {
        return data.slice(0, before) + separator + data.slice(nL-1-after, nL);
    } else {
        return data;
    }
}