Rails render partial Ajax Error BUT correct response shown in Debugger

Question

I'm trying to trigger an additionnal ajax query on an existing link using unobstrusive Javascript.

The Query is going to the server and processed, returning for the test the string "javascript template ok".

But, the ajax "success" function is never called. In place, it is the "error" function that is triggered...

I looked in the Chrome Debugger and I can see the response text coming back from the server, but never is the "success" method called... :-(

My call is

jQuery.ajax({
    type: 'POST',

    success: function(response) {   
        $("#details").html(response);
        console.log(response);
    },
    error: function(){ 
        alert("Error\nData could not be retrieve from the server");
    },
    url: '/treeview/show/1538.js',
    cache: false,
});

(url is harcoded in this example). The same Url in the browser gets the correct data with no layout :-)

Removing the ".js" in the url returns the html template with layout and the update of the "details" div is achieved correctly...

The controller is

    respond_to do |format|
      format.html # show.html.erb
      format.js   { render :inline => "JAVASCRIPT TEMPLATE !" }
    end

Thank you

EDIT :

Here is the object returned from the ajax query (first argument of error: function(jqXHR) ):

Object
    abort: function ( statusText ) {
    always: function () {
    complete: function () {
    done: function () {
    error: function () {
    fail: function () {
    getAllResponseHeaders: function () {
    getResponseHeader: function ( key ) {
    overrideMimeType: function ( type ) {
    pipe: function ( /* fnDone, fnFail, fnProgress */ ) {
    progress: function () {
    promise: function ( obj ) {
    readyState: 4
    responseText: "JAVASCRIPT TEMPLATE !"
    setRequestHeader: function ( name, value ) {
    state: function () {
    status: 200
    statusCode: function ( map ) {
    statusText: "OK"
    success: function () {
    then: function ( /* fnDone, fnFail, fnProgress */ ) {
    __proto__: Object

So I get the correct response text ??!! Where can be the error then ? :-s

Answer 1

You do not explicitly specify the dataType option for jQuery.ajax so jQuery infers it to be script (relying on MIME type served by Rails). Since JAVASCRIPT TEMPLATE ! is not a valid Javascript statement, parser error is thrown. There are two options to get success callback called instead of error:

Explicitly specify dataType as text:

jQuery.ajax({
    type: 'POST',
    dataType: 'text',
    // ...
});

Or return valid Javascript from controller:

respond_to do |format|
  format.html # show.html.erb
  format.js { render :inline => "{}" }
end

Answer 2

Have you considered that the response might get evaluated as javascript code and therefore throwing an error which gets caught?