In JS, when you write a for loop, the internal loop variable I will actually be saved in the function or class it runs, so you will find that when you batch-bind events to elements, i = the last one appears. The value of the loop variable is very confusing. There are two solutions.
The idea is: save this loop variable, do not let its scope be in the entire function, but within the loop body
1. Use closures (if you don’t understand closures, please open Baidu: www.baidu.com)
2. Use the with keyword, the with syntax is with(obj) { //so that you can directly use it here Access the properties of obj without adding obj.
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