Vue's DIFF algorithm is implemented by virtual DOM. When the state of Vue changes, Vue will generate a new virtual DOM tree correspondingly, and compare it with the old virtual DOM tree to find out which parts need to be updated.
Specifically, Vue's DIFF algorithm will traverse all the nodes of the old and new virtual DOM trees, and compare their tag names, attributes, child nodes and other information to determine whether they are the same. If the two nodes are different, Vue will replace the old node with the new node and update its child nodes to achieve local updates.
Of course, Vue's DIFF algorithm does not simply recursively traverse all nodes for comparison. It also has some optimization measures, such as for list rendering (v-for) and other scenarios, you can use a unique key to improve the efficiency of DIFF; in addition, when making comparisons, Vue will also use some heuristic algorithms, such as head and tail pointers way to reduce the number of comparisons as much as possible.
Generally speaking, Vue's DIFF algorithm is an efficient and accurate local update mechanism, which allows developers to achieve smooth user interface interaction on the premise of ensuring performance.