是否可以在javascript中滚动自己的“函数”构造或“评估”方法？

Question

Is it at all possible to re-implement 'function' or 'eval' in pure javascript? Eg lets say I wanted to be able to write the following:

// note that I don't want to have to put code in a string here
var x = func() { var something = "nothing"; return something; }

or

var hiString = 'hi'  // note that it of course needs to be able to access the current context
evaluatize("function hi(){ alert(hiString); } hi();")

Are either of these things possible in javascript?

Answer 1

您可以使用类似Narcissus的JavaScript编写JavaScript解释器。

Answer 2

for the first, I'm not sure if you were asking something different, but this works:

var x = function() {return "cake";}
x();

Answer 3

不，这是不可能的。

Answer 4

If your needs are simple, then you can do something like this:

var generator = function(input) {
    return function() {alert(input)};
};

var helloFunction = generator("Hello, World.");

helloFunction(); // alerts "Hello, World."