function digitLength(num) {
    // Get digit length of e
    var eSplit = num.toString().split(/[eE]/);
    var len = (eSplit[0].split('.')[1] || '').length - (+(eSplit[1] || 0));
    return len > 0 ? len : 0;
}
Return digits length of a number
@param {*number} num Input number