Downloading .csv from Express backend to Angularjs

I have seen this same question here, however the solution is not working in my case and inputting the code snipped that was used

$('<form action="'+ url +'" method="'+ ('post') +'">'+inputs+'</form>')
           .appendTo('body').submit().remove();

returns an error that Reference $ is not defined

I have a download request that looks like this:

controller.js

$http.put('/download' {file:$scope.inputInfo.name.$modelValue+'.csv'}).success(function(data,status,headers){
        console.log(status);
        console.log(data);

    })

app.js

app.put('/download', function(req,res){
    console.log(req.body.file)
    res.download(__dirname +'/'+ 'req.body.file, function(err){
      if(err){console.log(err)}
   })

})

My controller.js is returning the raw file output as data and not initiating the download from the page. Is there something I am missing to initiate this file download in angular? Any help would be greatly appreciated.