包含可执行函数代码的字符串 [英] String containing code to executable function

问题描述

$ b

  var code =function Solve（args）{/ /做东西并返回值};; 
  

转换为可传递参数的可执行函数。
当我将它与 eval（code +Solve（args）;）; 一起使用时，它没有给出任何错误，但结果与预期不符。我也试过：

  var fu = eval（code）; 
 var result = fu（args）; 
  

fu未定义。
我做错了什么，或者有更好的方法来做到这一点。

解决方案

使用eval通常是一种非常糟糕的做事方式。

$ b eval将把代码放到全局命名空间中

  var code =function Solve（args）{return args * 2}; 
 eval（code）; 
 var val = 1; 
 var result = Solve（val）; 
  

如果您不知道名称，则必须执行此类操作。

  var code =function Solve2（args）{return args * 2}; 
 var val = 3; 
 var result = eval（（+ code +）（+ val +）;）; 
  

上述方法的问题是它会使用toString（）

使用 new Function

  var sumCode =return a + b; 
 var sum = new函数（a，b，sumCode）; 
 sum（1,2）; 
  

I basically want to convert a string containing code like this -

var code = "function Solve(args) { // do stuff and return value};";

into an executable function which you can pass arguments. When I use it with eval(code + "Solve(args);"); It gives me no errors but the results are not as expected. I also tried:

var fu = eval(code);
var result = fu(args);

fu stays undefined. Am I doing something wrong or is there a better way to do this.

解决方案

Using eval is normally a very bad way of doing things.

eval is going to put the code into the Global namespace

var code = "function Solve(args) { return args * 2}";  
eval(code); 
var val = 1;
var result = Solve(val);

if you do not know the name, you would have to do something like this

var code = "function Solve2(args) { return args * 2}";
var val = 3;  
var result = eval("(" + code + ")(" + val + ");"); 

problem with the above method is it will use toString()

A better way to make a function from a string is using new Function

var sumCode = "return a + b";
var sum = new Function("a","b", sumCode);
sum(1,2); 

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