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doc: sort vm alphabetically
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Reorders, with no contextual changes, the vm documentation alphabetically.

PR-URL: #3662
Reviewed-By: Evan Lucas <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Jeremiah Senkpiel <[email protected]>
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@tflanagan
tflanagan authored and Myles Borins committed Nov 17, 2015
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296 changes: 143 additions & 153 deletions doc/api/vm.markdown
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Original file line number Diff line number Diff line change
Expand Up @@ -11,45 +11,125 @@ You can access this module with:
JavaScript code can be compiled and run immediately or compiled, saved, and run
later.

## vm.runInThisContext(code[, options])
## Class: Script

`vm.runInThisContext()` compiles `code`, runs it and returns the result. Running
code does not have access to local scope, but does have access to the current
`global` object.
A class for holding precompiled scripts, and running them in specific sandboxes.

Example of using `vm.runInThisContext` and `eval` to run the same code:
### new vm.Script(code, options)

Creating a new `Script` compiles `code` but does not run it. Instead, the
created `vm.Script` object represents this compiled code. This script can be run
later many times using methods below. The returned script is not bound to any
global object. It is bound before each run, just for that run.

The options when creating a script are:

- `filename`: allows you to control the filename that shows up in any stack
traces produced from this script.
- `displayErrors`: whether or not to print any errors to stderr, with the
line of code that caused them highlighted, before throwing an exception.
Applies only to syntax errors compiling the code; errors while running the
code are controlled by the options to the script's methods.

### script.runInContext(contextifiedSandbox[, options])

Similar to `vm.runInContext` but a method of a precompiled `Script` object.
`script.runInContext` runs `script`'s compiled code in `contextifiedSandbox`
and returns the result. Running code does not have access to local scope.

`script.runInContext` takes the same options as `script.runInThisContext`.

Example: compile code that increments a global variable and sets one, then
execute the code multiple times. These globals are contained in the sandbox.

var util = require('util');
var vm = require('vm');
var localVar = 'initial value';

var vmResult = vm.runInThisContext('localVar = "vm";');
console.log('vmResult: ', vmResult);
console.log('localVar: ', localVar);
var sandbox = {
animal: 'cat',
count: 2
};

var evalResult = eval('localVar = "eval";');
console.log('evalResult: ', evalResult);
console.log('localVar: ', localVar);
var context = new vm.createContext(sandbox);
var script = new vm.Script('count += 1; name = "kitty"');

// vmResult: 'vm', localVar: 'initial value'
// evalResult: 'eval', localVar: 'eval'
for (var i = 0; i < 10; ++i) {
script.runInContext(context);
}

`vm.runInThisContext` does not have access to the local scope, so `localVar` is
unchanged. `eval` does have access to the local scope, so `localVar` is changed.
console.log(util.inspect(sandbox));

In this way `vm.runInThisContext` is much like an [indirect `eval` call][1],
e.g. `(0,eval)('code')`. However, it also has the following additional options:
// { animal: 'cat', count: 12, name: 'kitty' }

- `filename`: allows you to control the filename that shows up in any stack
traces produced.
- `displayErrors`: whether or not to print any errors to stderr, with the
line of code that caused them highlighted, before throwing an exception.
Will capture both syntax errors from compiling `code` and runtime errors
thrown by executing the compiled code. Defaults to `true`.
- `timeout`: a number of milliseconds to execute `code` before terminating
execution. If execution is terminated, an `Error` will be thrown.
Note that running untrusted code is a tricky business requiring great care.
`script.runInContext` is quite useful, but safely running untrusted code
requires a separate process.

[1]: http://es5.github.io/#x10.4.2
### script.runInNewContext([sandbox][, options])

Similar to `vm.runInNewContext` but a method of a precompiled `Script` object.
`script.runInNewContext` contextifies `sandbox` if passed or creates a new
contextified sandbox if it's omitted, and then runs `script`'s compiled code
with the sandbox as the global object and returns the result. Running code does
not have access to local scope.

`script.runInNewContext` takes the same options as `script.runInThisContext`.

Example: compile code that sets a global variable, then execute the code
multiple times in different contexts. These globals are set on and contained in
the sandboxes.

var util = require('util');
var vm = require('vm');

var sandboxes = [{}, {}, {}];

var script = new vm.Script('globalVar = "set"');

sandboxes.forEach(function (sandbox) {
script.runInNewContext(sandbox);
});

console.log(util.inspect(sandboxes));

// [{ globalVar: 'set' }, { globalVar: 'set' }, { globalVar: 'set' }]

Note that running untrusted code is a tricky business requiring great care.
`script.runInNewContext` is quite useful, but safely running untrusted code
requires a separate process.

### script.runInThisContext([options])

Similar to `vm.runInThisContext` but a method of a precompiled `Script` object.
`script.runInThisContext` runs `script`'s compiled code and returns the result.
Running code does not have access to local scope, but does have access to the
current `global` object.

Example of using `script.runInThisContext` to compile code once and run it
multiple times:

var vm = require('vm');

global.globalVar = 0;

var script = new vm.Script('globalVar += 1', { filename: 'myfile.vm' });

for (var i = 0; i < 1000; ++i) {
script.runInThisContext();
}

console.log(globalVar);

// 1000

The options for running a script are:

- `displayErrors`: whether or not to print any runtime errors to stderr, with
the line of code that caused them highlighted, before throwing an exception.
Applies only to runtime errors executing the code; it is impossible to create
a `Script` instance with syntax errors, as the constructor will throw.
- `timeout`: a number of milliseconds to execute the script before terminating
execution. If execution is terminated, an `Error` will be thrown.

## vm.createContext([sandbox])

Expand All @@ -70,13 +150,11 @@ tags together inside that sandbox.

[2]: http://es5.github.io/#x15.1


## vm.isContext(sandbox)

Returns whether or not a sandbox object has been contextified by calling
`vm.createContext` on it.


## vm.runInContext(code, contextifiedSandbox[, options])

`vm.runInContext` compiles `code`, then runs it in `contextifiedSandbox` and
Expand Down Expand Up @@ -105,6 +183,18 @@ Note that running untrusted code is a tricky business requiring great care.
`vm.runInContext` is quite useful, but safely running untrusted code requires a
separate process.

## vm.runInDebugContext(code)

`vm.runInDebugContext` compiles and executes `code` inside the V8 debug context.
The primary use case is to get access to the V8 debug object:

var Debug = vm.runInDebugContext('Debug');
Debug.scripts().forEach(function(script) { console.log(script.name); });

Note that the debug context and object are intrinsically tied to V8's debugger
implementation and may change (or even get removed) without prior warning.

The debug object can also be exposed with the `--expose_debug_as=` switch.

## vm.runInNewContext(code[, sandbox][, options])

Expand Down Expand Up @@ -134,141 +224,41 @@ Note that running untrusted code is a tricky business requiring great care.
`vm.runInNewContext` is quite useful, but safely running untrusted code requires
a separate process.

## vm.runInThisContext(code[, options])

## vm.runInDebugContext(code)

`vm.runInDebugContext` compiles and executes `code` inside the V8 debug context.
The primary use case is to get access to the V8 debug object:

var Debug = vm.runInDebugContext('Debug');
Debug.scripts().forEach(function(script) { console.log(script.name); });

Note that the debug context and object are intrinsically tied to V8's debugger
implementation and may change (or even get removed) without prior warning.

The debug object can also be exposed with the `--expose_debug_as=` switch.
`vm.runInThisContext()` compiles `code`, runs it and returns the result. Running
code does not have access to local scope, but does have access to the current
`global` object.

Example of using `vm.runInThisContext` and `eval` to run the same code:

## Class: Script
var vm = require('vm');
var localVar = 'initial value';

A class for holding precompiled scripts, and running them in specific sandboxes.
var vmResult = vm.runInThisContext('localVar = "vm";');
console.log('vmResult: ', vmResult);
console.log('localVar: ', localVar);

var evalResult = eval('localVar = "eval";');
console.log('evalResult: ', evalResult);
console.log('localVar: ', localVar);

### new vm.Script(code, options)
// vmResult: 'vm', localVar: 'initial value'
// evalResult: 'eval', localVar: 'eval'

Creating a new `Script` compiles `code` but does not run it. Instead, the
created `vm.Script` object represents this compiled code. This script can be run
later many times using methods below. The returned script is not bound to any
global object. It is bound before each run, just for that run.
`vm.runInThisContext` does not have access to the local scope, so `localVar` is
unchanged. `eval` does have access to the local scope, so `localVar` is changed.

The options when creating a script are:
In this way `vm.runInThisContext` is much like an [indirect `eval` call][1],
e.g. `(0,eval)('code')`. However, it also has the following additional options:

- `filename`: allows you to control the filename that shows up in any stack
traces produced from this script.
traces produced.
- `displayErrors`: whether or not to print any errors to stderr, with the
line of code that caused them highlighted, before throwing an exception.
Applies only to syntax errors compiling the code; errors while running the
code are controlled by the options to the script's methods.


### script.runInThisContext([options])

Similar to `vm.runInThisContext` but a method of a precompiled `Script` object.
`script.runInThisContext` runs `script`'s compiled code and returns the result.
Running code does not have access to local scope, but does have access to the
current `global` object.

Example of using `script.runInThisContext` to compile code once and run it
multiple times:

var vm = require('vm');

global.globalVar = 0;

var script = new vm.Script('globalVar += 1', { filename: 'myfile.vm' });

for (var i = 0; i < 1000; ++i) {
script.runInThisContext();
}

console.log(globalVar);

// 1000

The options for running a script are:

- `displayErrors`: whether or not to print any runtime errors to stderr, with
the line of code that caused them highlighted, before throwing an exception.
Applies only to runtime errors executing the code; it is impossible to create
a `Script` instance with syntax errors, as the constructor will throw.
- `timeout`: a number of milliseconds to execute the script before terminating
Will capture both syntax errors from compiling `code` and runtime errors
thrown by executing the compiled code. Defaults to `true`.
- `timeout`: a number of milliseconds to execute `code` before terminating
execution. If execution is terminated, an `Error` will be thrown.


### script.runInContext(contextifiedSandbox[, options])

Similar to `vm.runInContext` but a method of a precompiled `Script` object.
`script.runInContext` runs `script`'s compiled code in `contextifiedSandbox`
and returns the result. Running code does not have access to local scope.

`script.runInContext` takes the same options as `script.runInThisContext`.

Example: compile code that increments a global variable and sets one, then
execute the code multiple times. These globals are contained in the sandbox.

var util = require('util');
var vm = require('vm');

var sandbox = {
animal: 'cat',
count: 2
};

var context = new vm.createContext(sandbox);
var script = new vm.Script('count += 1; name = "kitty"');

for (var i = 0; i < 10; ++i) {
script.runInContext(context);
}

console.log(util.inspect(sandbox));

// { animal: 'cat', count: 12, name: 'kitty' }

Note that running untrusted code is a tricky business requiring great care.
`script.runInContext` is quite useful, but safely running untrusted code
requires a separate process.


### script.runInNewContext([sandbox][, options])

Similar to `vm.runInNewContext` but a method of a precompiled `Script` object.
`script.runInNewContext` contextifies `sandbox` if passed or creates a new
contextified sandbox if it's omitted, and then runs `script`'s compiled code
with the sandbox as the global object and returns the result. Running code does
not have access to local scope.

`script.runInNewContext` takes the same options as `script.runInThisContext`.

Example: compile code that sets a global variable, then execute the code
multiple times in different contexts. These globals are set on and contained in
the sandboxes.

var util = require('util');
var vm = require('vm');

var sandboxes = [{}, {}, {}];

var script = new vm.Script('globalVar = "set"');

sandboxes.forEach(function (sandbox) {
script.runInNewContext(sandbox);
});

console.log(util.inspect(sandboxes));

// [{ globalVar: 'set' }, { globalVar: 'set' }, { globalVar: 'set' }]

Note that running untrusted code is a tricky business requiring great care.
`script.runInNewContext` is quite useful, but safely running untrusted code
requires a separate process.
[1]: http://es5.github.io/#x10.4.2

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