[BUG] creating chart when target element not on DOM yet

[pyalot]

Expected Behavior

It should work.

Current Behavior

An exception is thrown:

Uncaught TypeError: Cannot set property '_chartjs' of null

Possible Solution

Do not depend on parent element for watching resizes.

Steps to Reproduce (for bugs)

1. canvas = document.createElement('canvas');
2. chart = new Chart(canvas, ...);

Context

Trying to display a chart.

Environment

• Chart.js version: 2.4.0 (latest)
• Browser name and version: Any

[simonbrunel]

Chart.js doesn't support creating a responsive chart from an orphan canvas, and I don't think this will be fixed anytime soon since it would require to monitor extra DOM activity to know when the canvas is added to the tree (which may be beyond the library responsibility, /cc @chartjs/maintainers).

Depending on your use case, immediate alternatives are:

• if you don't need responsiveness, then turn it off via options: options: { responsive: false }
• else, make sure to insert your canvas in the tree before creating the chart

Note that this case should work fine when the new context acquisition method from a div node will be implemented (proposal).

[etanb]

+1 in having this issue.

[simonbrunel]

@pyalot It took some time but it should work now (#4591) :) Are you able to test this development build and confirm that it works as you expect?