"Can't get dom width or height" incorrectly fires for width/height values of 0.

[mixonic]

Version

4.2.1

Steps to reproduce

This warning from echarts: https://github.com/apache/incubator-echarts/blob/b6ab21159617b45c8077d998d468977cdd87d146/src/echarts.js#L1999 seems to be triggered when !dom.clientWidth, however I believe it is valid for dom.clientWidth to have a value of 0.

I'm not sure why this warning was added, but I think the check should be dom.clientWidth === undefined if the check is for a failure of the clientWidth API to exist.

What is expected?

warning should not occur for element width/height of 0

What is actually happening?

warning is logged.

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I'm happy to resolve this issue, but I'd like some confirmation my hunch is correct, or a clarification for why it is not.

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[Ovilia]

Why should 0 be a valid value for a container? The warning here is to warn users that the chart is not visible most likely because the container doesn't have width or height, in which case clientWidth or clientHeight is 0. Actually, they can never be undefined unless you assign so intentionally.

[mixonic]

@Ovilia A relative sized <div> may be 0 pixels in height or width before the chart is appended to that element. That is the case I'm getting the warning for.

The warning here is to warn users that the chart is not visible most likely because the container doesn't have width or height

The warning is specifically Can't get dom width or height. I think the original intent was to warn that a value could not be read at all, not that the chart might be invisible. For example the element in question could also be outside the screen, be visibility hidden, or display none and those things are not checked for.

But I'm not sure about original intent. Some history:

• Added in: 303140d#diff-4258186c56ec56760534e2b465bf3f81R1084
• Bug reported wrt: dom 定义了宽度和高度 为什么还是会提示Can't get dom width or height #4569

And afaict IE6 has support for clientHeight so I don't think it is an IE hack.

[Ovilia]

The width and height of the container are required to create a canvas with the same size. So none of 0 or null or undefined is valid when init. Although we could provide a default canvas size when container size is not given, it may cause some confusions (e.g., the user has defined canvas CSS width and height, and the size is not the same with canvas size).
Perhaps we should change the warning expression to make this information more understandable. But I don't think providing a default canvas size when container size is a very good idea. Because first of all, setting container size is not a hard job for the user to do, as long as they know what's wrong here. On the other hand, providing a default value that users don't know how to change (calling resize) is a bigger problem.