如何将进度元素设置为不确定

How to set a progress element to indeterminate

如何在设置值后将 progress 元素设置为不确定?

根据your documentation

If there is no value="" attribute, the progress bar is indeterminate; this indicates that an activity is ongoing with no indication of how long it is expected to take.

并且仍然根据文档:

To change the progress bar to indeterminate after giving it a value you must remove the value attribute with element.removeAttribute("value")