How to convert node.js date to SQL Server compatible datetime?

It seems that you haven't set the correct datetime value in addParameter function. According the API reference, the function is used as request.addParameter(name, type, value, [options]).

Please try the following code:

var query = "Insert into Proxy (Ip,RequisitionDate) values ( @ip , @date)";

request = new Request(query, function(err) {
    if (err) {
        console.log(err);}
    });

    request.addParameter('ip', TYPES.NVarChar,'<ip value>');
    request.addParameter('date', TYPES.DateTime , new Date());
// or the set the special date, refer to https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date
//  request.addParameter('RequisitionDate', TYPES.DateTime , new Date(2016,05,19,3,32,21))
    connection.execSql(request);
}

Any further concern, please feel free to let me know.