In Vue, key is a special attribute used to set a unique identifier for each node (component). It plays an important role in the rendering and updating process of Vue's virtual DOM, mainly in the following two aspects:
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Improve rendering efficiency When Vue is performing the diff algorithm of the virtual DOM to compare new and old nodes, if the nodes have the same key, Vue
will consider them to be the same node and will not re-render, thereby improving rendering efficiency. -
Keep component state When using the v-for command to render the list, each list item should have a unique key, so that when the order of the list items changes, Vue can accurately
determine which list items are newly added and which list items are Which list items already exist but have changed positions are deleted to maintain the correctness of the component state.
It should be noted that the key only works in its direct child components, if two components have the same key but they are not direct child components, Vue will still re-render them. In addition, the key should be stable and unique, and random numbers or indexes should not be used as keys, as this may cause rendering errors.