最近寫一個新頁面，涉及到非同步問題，為了獲得非同步過程中的資料，以下分享兩種方法；

兩種方法一句話總結：

方法一，Http請求後呼叫.then實現response的資料同步，然後根據resp接著處理；

方法二，使用ES6中的Promise語法糖，實現非同步等待resp；

方法一的程式碼：

其中invokeJsonRpc(RDS_CONFIG.APOLLO_CMDB_ENDPOINT_V3, "query.aggregate", queryParams)會發生一次HTTP請求

$("#submitFlushAll").on("click",function () {
        let clusterId 
 
= $("#cluster-id").val();
        const queryParams = {
            graph: `graph g {  redisCluster: RedisCluster[ id = "${clusterId}" ];}`,
            fields: [["redisCluster.name", "redisCluster.id", "redisCluster.used_memory"]]
        };
        invokeJsonRpc(RDS_CONFIG.APOLLO_CMDB_ENDPOINT_V3, 
 
"query.aggregate", queryParams).then(resp =>{
            let usedMemory = resp.result.children[0].data["redisCluster.used_memory"];
            let clusterName = $("#cluster-name").val();
            let details = {
                usedMemory : usedMemory,
                clusterName : clusterName,
            };
            let request 
 
= {
                title: `Redis清除${clusterName}的所有資料`,
                applicant: $("#username").val(),
                projectId: Number($("#project-id").val()),
                createTime: moment().format("YYYY-MM-DD HH:mm:ss"),
                resourceType: REDIS_JIGSAW_RESOURCE_TYPE,
                operationType: "redis_flush_all",
                resource: Number($("#resource-id").val()),
                sensitive: false,
                audit: true,
                carbonCopy: null,
                details: JSON.stringify(details),
                extension: null
            };
            submitJigsawWorkorder(request);
        });

方法二的程式碼：

注意Promise容器的構造，以及點選事件的處理函式為非同步；

    $("#submitFlushDatabase").on("click", async function () {
        let clusterId = $("#cluster-id").val();
        let usedMemoryPromise = fetchUsedMemeory(clusterId);
        let usedMemory = await Promise.all([usedMemoryPromise]);
        let databaseNumber = $("#inputDatabaseNumber").val();
        let clusterName = $("#cluster-name").val();
        let details = {
            databaseNumber : databaseNumber,
            clusterName : clusterName,
            usedMemory : usedMemory,
        };
        let request = {
            title: `Redis清除指定DB，指定DB：${databaseNumber}`,
            applicant: $("#username").val(),
            projectId: Number($("#project-id").val()),
            createTime: moment().format("YYYY-MM-DD HH:mm:ss"),
            resourceType: REDIS_JIGSAW_RESOURCE_TYPE,
            operationType: "redis_flush_database",
            resource: Number($("#resource-id").val()),
            sensitive: false,
            audit: true,
            carbonCopy: null,
            details: JSON.stringify(details),
            extension: null
        };
        submitJigsawWorkorder(request);
    });

    async function fetchUsedMemeory(clusterId) {
        const queryParams = {
            graph: `graph g {  redisCluster: RedisCluster[ id = "${clusterId}" ];}`,
            fields: [["redisCluster.name", "redisCluster.id", "redisCluster.used_memory"]]
        };
        let resp = await invokeJsonRpc(RDS_CONFIG.APOLLO_CMDB_ENDPOINT_V3, "query.aggregate", queryParams);
        let usedMemory = resp.result.children[0].data["redisCluster.used_memory"];
        return usedMemory;
    }

兩種方法的比較：使用Promise語法糖會使得程式碼結構性更加清晰，易讀。

Promise學習可以參考這個連結：https://blog.csdn.net/major_zhang/article/details/79154287