javascript - 在闭包作用域中设置变量

Question

我想我明白为什么变量存在于它们声明的函数之外，因为你正在返回另一个函数:

myFunction = function() {
    var closure = 'closure scope'
    return function() {
        return closure;
    }
}
A = myFunction(); // myFunction returns a function, not a value
B = A(); // A is a function, which when run, returns:
console.log(B); // 'closure scope'

按照现在的写法，调用 A() 就像一个 getter。

问:如何编写 myFunction 以便调用 A(123) 是一个 setter？

Answer 1

尝试以下操作:

myFunction = function() {
    var closure = 'closure scope'

    // value is optional
    return function(value) {
        // if it will be omitted
        if(arguments.length == 0) {
            // the method is a getter
            return closure;
        } else {
            // otherwise a setter
            closure = value;
            // with fluid interface ;)
            return this;
        }
    }
}
A = myFunction(); // myFunction returns a function, not a value
A(123); // set value
B = A(); // A is a function, which when run, returns:
console.log(B); // '123'