给定名称作为函数的字符串参数，是否可以编写一个对全局变量动态操作的函数？

Question

Is it possible to pass a string which names a global variable to a function which in turn operates on that variable in the global context?

Sample function:

// the parameter str may be a global like:  `"localStorage"`, `"sessionStorage"`.
function (str, key, value){
  // the `converted_str` means the `localStorage` or `sessionStorage`
  converted_str.setItem(key, value)
}

---

EDIT-1

How about other case, such as this or not window global variable？

Answer 1

If by system variable you mean global variable (which it appears you do), then yes:

function (str, key, value){
  window[str].setItem(key, value)
}

In a browser, global variables are members of the global window object, and can be accessed dynamically through that object.

For non-globals:

If it is a member of the current this object, you can use:

something.method = function (str, key, value){
    this[str].setItem(key, value)
};

Alternately, if you just have some variables you want to access dynamically, just put them in your own object.

var obj = {
    'something': function() {}
};

var str = 'something';
obj[str]();