• 需求：模仿PC企业微信聊天记录，实现向上滚动加载上一页，并处理滚动条位置

1、监听聊天记录的滚动

// <template>
<div class="chat-history" ref="chatHistory" @scroll="handleScroll"></div>

2、添加监听事件

// <script setup>
const chatHistory = ref(null);
const preSrollHeight = ref(0);
const hasMoreHistory = ref(true);

function handleScroll() {
    if(hasMoreHistory.value === false) {
        return
    }
    const container = chatHistory.value;
    if (container.scrollTop <= 1 ) {
        if(refreshing.value) {
            return
        }
        refreshing.value = true;
        chatHistoryList()
    }
}

3、获取历史消息里面

// 获取历史消息
function chatHistoryList() {
    const params = {
        userId: userStore.userInfo.web_user_id,
        friendId: userStore.userInfo.character_being_used,
        seqId: useUserStore.seqId ? useUserStore.seqId : "0",
        limit: 20,
        token: userStore.token,
        header: userStore?.header,
    };
    getChatHistory(params, (err, response) => {
        if (err) {
            // 处理错误
            ElMessage.error(t('network.failedReceiveHistoryMessage'));
        } else {
            // 处理成功的响应
            // ElMessage({
            //     showClose: false,
            //     message: "获取历史消息成功",
            //     type: "success",
            // });
            if(response?.chatMessagesList.length == 0) {
                hasMoreHistory.value = false
            }else {
                hasMoreHistory.value = true
            }
            messages.value.unshift(...response?.chatMessagesList);
            formatMessages();
            const lastMessage = messages.value[messages.value.length - 1];
            topicState(lastMessage);
            if (isFirstLoad.value) {
                scrollToBottom();
                isFirstLoad.value = false;
            }
            const scrollTop = chatHistory.value.scrollHeight - preSrollHeight.value;
            chatHistory.value.scrollTop = scrollTop;
            preSrollHeight.value = chatHistory.value.scrollHeight;
            nextTick(() => {
                let heigh = chatHistory.value.scrollHeight;
                let sroll = heigh - preSrollHeight.value;
                chatHistory.value.scrollTo(0, sroll);
                preSrollHeight.value = heigh;
            })}
        // 数据加载完成后，设置 refreshing 为 false
        refreshing.value = false;
    });
}

参考链接