每次 for 循环迭代都会重置全局变量，而不是更新

Question

披露：我是新手，对 JS 缺乏经验，但我花了几个小时试图通过 Stackoverflow 和其他互联网资源找到解决方案。我的导师这周不在，所以我希望这里的人能够帮助我。提前谢谢！

简介：我正在尝试通过变量 setupTotal 跟踪运行总计。我将它放在函数 getStoredData 的顶部，认为它会像一个全局函数一样在 getStoredData 中的 for 循环期间被覆盖或重置。我已经包含了上下文的周围代码，并将我认为与我遇到的实际问题相关的内容加粗。

问题： 每次 for 循环通过迭代循环时，我的 setupTotal 变量都会被重置。我在控制台日志和 buildSetup 函数末尾的 setupFees.innerHTML 中都看到了这一点。据我了解，当我指定 var setupTotal = 0;在 getStoredData 函数的开头，我在 buildSetup 嵌套函数中所做的更新应该覆盖原始值。然而，每次运行新的迭代时，setupTotal 值又从 0 开始。

---

function getStoredData() {

    // Builds "Service Row" div to house the incoming content
    buildDivRow();

    var setupTotal = 0;

    // Loops through the boxes to see what's stored
    for (var service in serviceDatabase) {

        for (id=0; id < serviceDatabase[service].length; id++) {

        console.log("Starting " + service + ": " + serviceDatabase[service][id]);

            // Get the stored data if it exists
            var inputID = service + "-input-" + id;
            var getData = localStorage.getItem(inputID);
            console.log("Attempting data retrieval for " + inputID + ": " + getData);

            // Passes the info to a function that creates the HTML to display stored data
            if (getData != null) {

                // Passes the info to functions that captures "total" data
                console.log("buildSetup starting, service: " + service);
                console.log("buildSetup starting, getData: " + getData);
                console.log("buildSetup starting, setupTotal): " + setupTotal);
                buildSetup(service, getData, setupTotal);

                // Passes the info to a function that builds the div containers
                buildDivXs12(getData, inputID, service, id);

                // Logs that the data was found successfully or not
                console.log("Retrieved ID (" + inputID + ") and data (" + getData + ")");
            } else {
                console.log("No data to retrieve for " + serviceDatabase[service][id] + ": " + inputID );
            }
        }
    }
}

// Keeps track of the setup fees
function buildSetup(service, getData, setupTotal) {

    // Retrieve the setup fee
    var setup = setupDatabase[service][getData];
    console.log("buildSetup ending, setup: " + setup);

    // Update the setupTotal global var
    setupTotal = parseInt(setupTotal) + parseInt(setup);
    console.log("buildSetup ending, setupTotal): " + setupTotal);

    // Update the setupFees inner HTML
    var setupFees = document.getElementById("setupFee");
    setupFees.innerHTML = setupTotal;
}

Answer 1

根据您的代码，您可以做的是在 buildSetup 函数上返回 setupTotal 值，然后在 getStoredData 上调用它后分配它函数如下：

function getStoredData() {
  ..
  console.log("buildSetup starting, setupTotal): " + setupTotal);
  setupTotal = buildSetup(service, getData, setupTotal);
  ..
}

function buildSetup(service, getData, setupTotal) {
  ..
  setupFees.innerHTML = setupTotal;

  return setupTotal;
}