Uncaught TypeError in Google Chrome 22.0.1201.0 canary

[martinnormark]

In the latest couple of Google Chrome Canary builds, Backbone.Model.extend({}) throws an error:

Uncaught TypeError: Object function (a,b){var c;a||(a={});b&&b.parse&&(a=this.parse(a));if(c=n(this,"defaults"))a=f.extend({},c,a);b&&b.collection&&(this.collection=b.collection);this.attributes={};this._escapedAttributes={};this.cid=f.uniqueId("c");this.changed={};this._silent=
{};this._pending={};this.set(a,{silent:!0});this.changed={};this._silent={};this._pending={};this._previousAttributes=f.clone(this.attributes);this.initialize.apply(this,arguments)} has no method '_bindRoutes' 

This might be a Chrome issue, but it might be worth further investigation to avoid it ending up in one of the stable builds of Chrome, if this be a breaking change in Chrome.

Repro

1. Go to http://backbonejs.org/
2. Open the Chrome DevTools console.
3. Type Backbone.Model.extend({}) and hit return.

[jashkenas]

Whoa -- you're quite right. I'm seeing the same problem on DocumentCloud.org. Even though it will likely be fixed before getting pushed to Chrome proper -- let's get this sorted out.

[knowtheory]

I've done some poking around, and for whatever reason, both Backbone.Collection and Backbone.Model are having their extend function set to the Backbone.Router's constructor function.

This is particularly weird because all of the extend functions are declared at the same time:

Model.extend = Collection.extend = Router.extend = View.extend = extend;

And Router and View have their extend functions set correctly.

[knowtheory]

This is some truly bizarre behavior.

Replacing that line with:

    // Set up inheritance for the model, collection, and view.
    console.log(extend);
    console.log(View.extend = extend);
    console.log(Router.extend = extend);
    console.log(Collection.extend = extend);
    console.log(Model.extend = extend);

Results in the following behavior (the first assignment returns correctly, compare the results from line 1312 and 1313. The return value on 1314 is the constructor for Backbone.Router, 1315 is Backbone.Collection's and 1316 is Backbone.Model's.):

function (protoProps, classProps) {
    var child = inherits(this, protoProps, classProps);
    child.extend = this.extend;
    return child;
  } backbone.js:1312
function (protoProps, classProps) {
    var child = inherits(this, protoProps, classProps);
    child.extend = this.extend;
    return child;
  } backbone.js:1313
function (options) {
    options || (options = {});
    if (options.routes) this.routes = options.routes;
    this._bindRoutes();
    this.initialize.apply(this, arguments);
  } backbone.js:1314
function (models, options) {
    options || (options = {});
    if (options.model) this.model = options.model;
    if (options.comparator !== undefined) this.comparator = options.comparator;
    this._reset();
    this.initialize.apply(this, arguments);
    if (models) this.reset(models, {silent: true, parse: options.parse});
  } backbone.js:1315
function (attributes, options) {
    var defaults;
    attributes || (attributes = {});
    if (options && options.collection) this.collection = options.collection;
    if (options && options.parse) attributes = this.parse(attributes);
    if (defaults = getValue(this, 'defaults')) {
      attributes = _.extend({}, defaults, attributes);
    }
    this.attributes = {};
    this._escapedAttributes = {};
    this.cid = _.uniqueId('c');
    this.changed = {};
    this._silent = {};
    this._pending = {};
    this.set(attributes, {silent: true});
    // Reset change tracking.
    this.changed = {};
    this._silent = {};
    this._pending = {};
    this._previousAttributes = _.clone(this.attributes);
    this.initialize.apply(this, arguments);
  } 

More interestingly however,

when you check Backbone.Model.extend, it seems to have correctly assigned the appropriate function body:

function (protoProps, classProps) {
    var child = inherits(this, protoProps, classProps);
    child.extend = this.extend;
    return child;
  }

So it looks like Canary is assigning correctly, but is returning function bodies unpredictably.

[knowtheory]

I've filed this: https://code.google.com/p/chromium/issues/detail?id=136381

[martinnormark]

Awesome!

Or, it looks very weird -- I spent two hours troubleshooting my code before I realized this was beyond me :)

I had an error with the Highcharts library some time ago, and it took quite a long time before that was corrected in the Canary build.

[jashkenas]

I'm going to close it for us then -- it seems pretty clearly like something we shouldn't worry about.

[leshill]

Just for anyone looking, the bug seems to be present in 22.0.1199.0 as well.

[jrolfs]

I'm on 22.0.1202.0 and I'm getting some really erratic behavior. In addition to the extend() issue, _bindRoutes() on the Router is undefined. Really hope they sort this out soon I miss my Canary Web Inspector.

[heyvito]

Same behavior on Chrome 22.0.1201.0 dev-m

[phillycoder]

my backbone.js site working fine since this morning, after i did chrome update to 22.0.1201.0 dev-m, i am getting "has no method '_bindRoutes'" error when defining a model. Is this chrome browser bug?

Even backbone official sample todo app not working.

[jocafa]

Same here. I'm running Version 22.0.1201.0 dev. I hope this issue doesn't make it through the dev channel into release.

[Jabbslad]

FYI - I think the underlying issue has been fixed in V8 now guys so I expect things to good again in the next Chrome dev build :) http://code.google.com/p/v8/issues/detail?id=2226

[heyvito]

Hope so :(