HTML收集的突变观察者

Question

我正在尝试在页面中添加新元素的突变观察。但是我下面的代码在页面中加载新元素时并未显示“更改观察”。

setTimeout(() => {
    const observer = new MutationObserver(mutations => {
        console.log("change obervered!!!")
        console.log(mutations)
        var seconds = new Date().getTime() / 1000
        console.log(seconds)
        dict["Paul Yang"] = seconds

    })
    targets = document.getElementsByClassName("XEazBc adnwBd")
    length = document.getElementsByClassName('XEazBc adnwBd').length


    console.log(targets)

    console.log("length is: ", length)
    for (let i = 0; i < length; i++) {
        console.log("add one observer")
        observer.observe(targets.item(i), {
            childList: true,
            attributes: true,
            characterData: true,
            subtree: true,
        })
    }
}, 2000);