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vm 沙箱模块

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• runInThisContext：在全局上下文中执行

一个node.js文件中的作用域是使用函数function (exports,module,require,__direname,filename){ }包裹过后的，也即：

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const vm = require("vm");

global.a = 1;

var b = 2;

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vm.runInThisContext("console.log(typeof a)"); //number

vm.runInThisContext("console.log(typeof this.a)"); //number this相当于global

vm.runInThisContext("console.log(typeof b)"); //undefined

vm.runInThisContext("console.log(typeof require)"); //undefined

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• runInNewContext是在一个全新的作用域下执行，也即拿不到global的属性

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const vm = require("vm");

global.a = 1;

var b = 2;

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let obj = {c:3}

vm.runInNewContext("a = typeof a",obj);

vm.runInNewContext("b = typeof b",obj);

vm.runInNewContext("global = typeof global",obj);

vm.runInNewContext("c = typeof c",obj);

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console.log(obj);//{ c: 'number', a: 'undefined', b: 'undefined', global: 'undefined' }