模块中的 JavaScript 跨文件私有(private)状态

Question

我正在阅读一篇文章 here ，想知道这段代码是什么意思？特别是这种赋值有什么作用 var _private = my._private = my._private || {}?

var MODULE = (function (my) {
    var _private = my._private = my._private || {},
        _seal = my._seal = my._seal || function () {
            delete my._private;
            delete my._seal;
            delete my._unseal;
        },
        _unseal = my._unseal = my._unseal || function () {
            my._private = _private;
            my._seal = _seal;
            my._unseal = _unseal;
        };

    // permanent access to _private, _seal, and _unseal

    return my;
}(MODULE || {}));

Answer 1

你只需要分解它。

var _private = my._private = my._private || {}?

你有两个部分。

第一个是:

my._private = my._private || {}?

这是covered by this question .

如果左侧为真，则 || 运算符解析为左侧，否则为右侧。

第二个是:

var _private = my._private = something

这是covered by this question .

something 的值被分配给 my._private 然后 my._private 的新值被分配给 _private ，这是一个局部范围的变量，因为 it has var .