vm.runInThisContext(code[, options])
code
<string> 要编译和运行的 JavaScript 代码。options
<Object> | <string>filename
<string> 指定此脚本生成的堆栈跟踪中使用的文件名。 默认值:'evalmachine.<anonymous>'
。lineOffset
<number> 指定在此脚本生成的堆栈跟踪中显示的行号偏移量。 默认值:0
。columnOffset
<number> 指定在此脚本生成的堆栈跟踪中显示的第一行列号偏移量。 默认值:0
。displayErrors
<boolean> 当为true
时,如果编译code
时出现Error
,则导致错误的代码行会附加到堆栈跟踪中。 默认值:true
。timeout
<integer> 指定终止执行前执行code
的毫秒数。 如果执行终止,则将抛出Error
。 此值必须是严格的正整数。breakOnSigint
<boolean> 如果为true
,则接收SIGINT
(Ctrl+C)将终止执行并抛出Error
。 已通过process.on('SIGINT')
附加的事件的现有句柄在脚本执行期间被禁用,但在此之后继续工作。 默认值:false
。cachedData
<Buffer> | <TypedArray> | <DataView> 为所提供的源提供可选的Buffer
或TypedArray
或DataView
,其中包含 V8 的代码缓存数据。importModuleDynamically
<Function> 在调用import()
时在评估此模块期间调用。 如果未指定此选项,则调用import()
将使用ERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING
拒绝。 此选项是实验模块 API 的一部分。 不建议在生产环境中使用它。specifier
<string> 传给import()
的说明符script
<vm.Script>importAssertions
<Object> 传给optionsExpression
可选参数的"assert"
值,如果没有提供值,则为空对象。- 返回: <Module Namespace Object> | <vm.Module> 建议返回
vm.Module
以利用错误跟踪,并避免包含then
函数导出的命名空间出现问题。
- 返回: <any> 脚本中执行的最后一条语句的结果。
vm.runInThisContext()
编译 code
,在当前 global
的上下文中运行它并返回结果。
运行代码无权访问局部作用域,但可以访问当前 global
对象。
如果 options
是字符串,则指定文件名。
以下示例说明使用 vm.runInThisContext()
和 JavaScript eval()
函数来运行相同的代码:
const vm = require('node:vm');
let localVar = 'initial value';
const vmResult = vm.runInThisContext('localVar = "vm";');
console.log(`vmResult: '${vmResult}', localVar: '${localVar}'`);
// 打印: vmResult: 'vm', localVar: 'initial value'
const evalResult = eval('localVar = "eval";');
console.log(`evalResult: '${evalResult}', localVar: '${localVar}'`);
// 打印: evalResult: 'eval', localVar: 'eval'
因为 vm.runInThisContext()
无权访问本地作用域,所以 localVar
不变。
相比之下,eval()
确实有权访问本地作用域,因此值 localVar
已更改。
这样 vm.runInThisContext()
很像 间接 eval()
调用,例如 (0,eval)('code')
。
code
<string> The JavaScript code to compile and run.options
<Object> | <string>filename
<string> Specifies the filename used in stack traces produced by this script. Default:'evalmachine.<anonymous>'
.lineOffset
<number> Specifies the line number offset that is displayed in stack traces produced by this script. Default:0
.columnOffset
<number> Specifies the first-line column number offset that is displayed in stack traces produced by this script. Default:0
.displayErrors
<boolean> Whentrue
, if anError
occurs while compiling thecode
, the line of code causing the error is attached to the stack trace. Default:true
.timeout
<integer> Specifies the number of milliseconds to executecode
before terminating execution. If execution is terminated, anError
will be thrown. This value must be a strictly positive integer.breakOnSigint
<boolean> Iftrue
, receivingSIGINT
(Ctrl+C) will terminate execution and throw anError
. Existing handlers for the event that have been attached viaprocess.on('SIGINT')
are disabled during script execution, but continue to work after that. Default:false
.cachedData
<Buffer> | <TypedArray> | <DataView> Provides an optionalBuffer
orTypedArray
, orDataView
with V8's code cache data for the supplied source.importModuleDynamically
<Function> Called during evaluation of this module whenimport()
is called. If this option is not specified, calls toimport()
will reject withERR_VM_DYNAMIC_IMPORT_CALLBACK_MISSING
. This option is part of the experimental modules API. We do not recommend using it in a production environment.specifier
<string> specifier passed toimport()
script
<vm.Script>importAssertions
<Object> The"assert"
value passed to theoptionsExpression
optional parameter, or an empty object if no value was provided.- Returns: <Module Namespace Object> | <vm.Module> Returning a
vm.Module
is recommended in order to take advantage of error tracking, and to avoid issues with namespaces that containthen
function exports.
- Returns: <any> the result of the very last statement executed in the script.
vm.runInThisContext()
compiles code
, runs it within the context of the
current global
and returns the result. Running code does not have access to
local scope, but does have access to the current global
object.
If options
is a string, then it specifies the filename.
The following example illustrates using both vm.runInThisContext()
and
the JavaScript eval()
function to run the same code:
const vm = require('node:vm');
let localVar = 'initial value';
const vmResult = vm.runInThisContext('localVar = "vm";');
console.log(`vmResult: '${vmResult}', localVar: '${localVar}'`);
// Prints: vmResult: 'vm', localVar: 'initial value'
const evalResult = eval('localVar = "eval";');
console.log(`evalResult: '${evalResult}', localVar: '${localVar}'`);
// Prints: evalResult: 'eval', localVar: 'eval'
Because vm.runInThisContext()
does not have access to the local scope,
localVar
is unchanged. In contrast, eval()
does have access to the
local scope, so the value localVar
is changed. In this way
vm.runInThisContext()
is much like an indirect eval()
call, e.g.
(0,eval)('code')
.