javascript - 如果您使 javascript 中的已用对象无效，您是否正在保存可能的愚蠢垃圾收集？

Question

如果您在 javascript 中使用过的对象无效，您是在节省可能的愚蠢垃圾回收吗？

例如。

如果您在 javascript 中遍历某些用户:

var users = [
    { FirstName: "Chris", LastName: "Pearson" },
    { FirstName: "Kate", LastName: "Johnson" },
    { FirstName: "Josh", LastName: "Sutherland" },
    { FirstName: "John", LastName: "Ronald" },
    { FirstName: "Steve", LastName: "Pinkerton" }
];

// Do something with the data, perhaps put it in a table

users = null;

现在是否值得取消该列表？有没有人了解性能提升背后的科学原理，或者这是在浪费时间等？

有时很难向人们解释你为什么要以某种方式做某事，我知道它在很多情况下保存了我的培根，当然，C++，但在 javascript 中，是否有任何实验来找出它是否值得javascript？找到一个我可以信任的 sizeof 函数，这让我哭了......如果有人已经做过这种实验，我将非常感激看到你的成果!

Answer 1

视情况而定。例如这里是没用的:

function putUsersInTable(){
    var users = [
        { FirstName: "Chris", LastName: "Pearson" },
        { FirstName: "Kate", LastName: "Johnson" },
        { FirstName: "Josh", LastName: "Sutherland" },
        { FirstName: "John", LastName: "Ronald" },
        { FirstName: "Steve", LastName: "Pinkerton" }
    ];

    // Do something with the data

    users = null; // Useless, the data could be GC'd anyways
}

这里它将允许数据在其他情况下不能被 GC 处理:

function putUsersInTable(){
    var users = [
        { FirstName: "Chris", LastName: "Pearson" },
        { FirstName: "Kate", LastName: "Johnson" },
        { FirstName: "Josh", LastName: "Sutherland" },
        { FirstName: "John", LastName: "Ronald" },
        { FirstName: "Steve", LastName: "Pinkerton" }
    ];

    // Do something with the data

    // This could be an event hander in the DOM or any global variable
    outsidethisscope = function(){
        // This anonymous function has access to users,
        // But doesn't necessarily make use of it
        console.log('Hi');
    }

    users = null; // Removes the only reference to that array, 
                  // allowing it to be GC'd
}