TypeError: Cannot define property:__v-for__1, object is not extensible.

[sirlancelot]

I have a list of objects to which I don't need observation to happen. The recommended way I've read about is to use Object.freeze() which works great except when I need to iterate over frozen objects in an array.

Vue.js version

1.0.21

Reproduction Link

http://codepen.io/sirlancelot/pen/aNPaNZ

Steps to reproduce

• Create an array of frozen objects with Object.freeze()
• The array should NOT be frozen, just the items within it.
• Iterate over the array with v-for=""

What is Expected?

Array is rendered without errors.

What is actually happening?

An error is emitted in the console: Uncaught TypeError: Cannot define property:__v-for__1, object is not extensible.

[yyx990803]

When v-for is rendered with data objects and has no track-by key, it will attempt to add a hidden key to the objects in order to track them. When the object is frozen, this strategy cannot be used, so you need to explicitly use a track-by key in this case. I've added a warning for it.

[sirlancelot]

Thanks! I submitted a PR to update the documentation for this as well.