更改删除课程的文字

Question

我希望在另一个javascript文件从中删除特定类之后更改项目的文本。如果我无法访问正在删除类的javascript，如何在类删除时触发事件？

Answer 1

你可以使用变异观察者：

let observer = new MutationObserver(function(mutationsList) {
  for (let mutation of mutationsList) {
    // this if is necessary if you want to observe a lot of different things by one observer
    if (mutation.type == "attributes" && mutation.target == elementYouWantToObserveClassChanges && mutation.attributeName == "class") {
      // mutation.oldValue now contains old class attribute
      // current classes can be checked in normal way using .className or .classList properties)
    }
  }
});

observer.observe(elementYouWantToObserveClassChanges, {attributes: true, attributeFilter: ['class']});

代码基于https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver

的示例