javascript - 如何在 eval() 中评估 console.log(1+2) ？

Question

我尝试通过 Node 控制台发送参数并希望在 eval 函数内执行它。

我在控制台中写的是:

node main console.log(1+1)

main.js 文件是这样的:

var x = "";
process.argv.forEach(function (val, index, array) {
  console.log(index + ': ' + val);
  x = val;
});

var eval = require('eval')
eval("(" + x + ")");

它会抛出这个错误:

D:\Sandbox\jsdom>node main console.log(1+2)
0: C:\Program Files\nodejs\node.exe
1: D:\Sandbox\jsdom\main
2: console.log(1+2)

evalmachine.<anonymous>:1
(console.log(1+2))
 ^
ReferenceError: console is not defined
    at evalmachine.<anonymous>:1:2
    at ContextifyScript.Script.runInContext (vm.js:35:29)
    at ContextifyScript.Script.runInNewContext (vm.js:41:15)
    at module.exports (D:\Sandbox\jsdom\node_modules\eval\eval.js:69:12)
    at Object.<anonymous> (D:\Sandbox\jsdom\main.js:11:1)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)

有人知道我做错了什么吗？

我在控制台中期望的输出是:

3

谢谢

Answer 1

您需要将console scope传递给eval。例如:

var x = "";
process.argv.forEach(function (val, index, array) {
  console.log(index + ': ' + val);
  x = val;
});

var eval = require('eval')
eval(x, null, 'console');

调用时:

node app.js "console.log(1+1)"

输出:

2