Some routes cannot be fully configured, or even discovered, until your application performs I/O. parse() never performs I/O. Instead it pauses at a phase boundary and returns a step. Your application does the I/O, then calls resume() on the step with the result.
Two elements create a phase boundary:
checkpoint() pauses so you can load configuration, then resume with value sources.
dynamic(schema, extension) pauses so you can supply any value, then adds options or routes built from it.
The real gh reads its configuration from the directory in GH_CONFIG_DIR. Declare that option before checkpoint(), and everything after the checkpoint is parsed once the configuration is loaded:
The process.argv property returns an array containing the command-line
arguments passed when the Node.js process was launched. The first element will
be
execPath
. See process.argv0 if access to the original value
of argv[0] is needed. The second element will be the path to the JavaScript
file being executed. The remaining elements will be any additional command-line
arguments.
For example, assuming the following script for process-args.js:
Returns a copy of a section of an array.
For both start and end, a negative index can be used to indicate an offset from the end of the array.
For example, -2 refers to the second to last element of the array.
@param ― start The beginning index of the specified portion of the array.
If start is undefined, then the slice begins at index 0.
@param ― end The end index of the specified portion of the array. This is exclusive of the element at the index 'end'.
If end is undefined, then the slice extends to the end of the array.
It is possible to modify this object, but such modifications will not be
reflected outside the Node.js process, or (unless explicitly requested)
to other Worker threads.
In other words, the following example would not work:
Assigning a property on process.env will implicitly convert the value
to a string. This behavior is deprecated. Future versions of Node.js may
throw an error when the value is not a string, number, or boolean.
import{ env }from'node:process';
env.test =null;
console.log(env.test);
// => 'null'
env.test =undefined;
console.log(env.test);
// => 'undefined'
Use delete to delete a property from process.env.
import{ env }from'node:process';
env.TEST=1;
delete env.TEST;
console.log(env.TEST);
// => undefined
On Windows operating systems, environment variables are case-insensitive.
import{ env }from'node:process';
env.TEST=1;
console.log(env.test);
// => 1
Unless explicitly specified when creating a Worker instance,
each Worker thread has its own copy of process.env, based on its
parent thread's process.env, or whatever was specified as the env option
to the Worker constructor. Changes to process.env will not be visible
across Worker threads, and only the main thread can make changes that
are visible to the operating system or to native add-ons. On Windows, a copy of process.env on a Worker instance operates in a case-sensitive manner
unlike the main thread.
The console module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.
The module exports two specific components:
A Console class with methods such as console.log(), console.error() and console.warn() that can be used to write to any Node.js stream.
A global console instance configured to write to process.stdout and
process.stderr. The global console can be used without importing the node:console module.
Warning: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the note on process I/O for
more information.
Example using the global console:
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s','world');
// Prints: hello world, to stdout
console.error(newError('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
// Error: Whoops, something bad happened
// at [eval]:5:15
// at Script.runInThisContext (node:vm:132:18)
// at Object.runInThisContext (node:vm:309:38)
// at node:internal/process/execution:77:19
// at [eval]-wrapper:6:22
// at evalScript (node:internal/process/execution:76:60)
// at node:internal/main/eval_string:23:3
constname='Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
Example using the Console class:
constout=getStreamSomehow();
consterr=getStreamSomehow();
constmyConsole=new console.Console(out, err);
myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s','world');
// Prints: hello world, to out
myConsole.error(newError('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err
Prints to stderr with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to printf(3)
(the arguments are all passed to util.format()).
constcode=5;
console.error('error #%d', code);
// Prints: error #5, to stderr
console.error('error', code);
// Prints: error 5, to stderr
If formatting elements (e.g. %d) are not found in the first string then
util.inspect() is called on each argument and the
resulting string values are concatenated. See util.format()
for more information.
NodeJS.Process.exit(code?: number | string |null): never
The process.exit() method instructs Node.js to terminate the process
synchronously with an exit status of code. If code is omitted, exit uses
either the 'success' code 0 or the value of process.exitCode if it has been
set. Node.js will not terminate until all the 'exit' event listeners are
called.
To exit with a 'failure' code:
import{ exit }from'node:process';
exit(1);
The shell that executed Node.js should see the exit code as 1.
Calling process.exit() will force the process to exit as quickly as possible
even if there are still asynchronous operations pending that have not yet
completed fully, including I/O operations to process.stdout and process.stderr.
In most situations, it is not actually necessary to call process.exit() explicitly. The Node.js process will exit on its own if there is no additionalwork pending in the event loop. The process.exitCode property can be set to
tell the process which exit code to use when the process exits gracefully.
For instance, the following example illustrates a misuse of the process.exit() method that could lead to data printed to stdout being
truncated and lost:
import{ exit }from'node:process';
// This is an example of what *not* to do:
if(someConditionNotMet()){
printUsageToStdout();
exit(1);
}
The reason this is problematic is because writes to process.stdout in Node.js
are sometimes asynchronous and may occur over multiple ticks of the Node.js
event loop. Calling process.exit(), however, forces the process to exit before those additional writes to stdout can be performed.
Rather than calling process.exit() directly, the code should set the process.exitCode and allow the process to exit naturally by avoiding
scheduling any additional work for the event loop:
import process from'node:process';
// How to properly set the exit code while letting
// the process exit gracefully.
if(someConditionNotMet()){
printUsageToStdout();
process.exitCode =1;
}
If it is necessary to terminate the Node.js process due to an error condition,
throwing an uncaught error and allowing the process to terminate accordingly
is safer than calling process.exit().
In Worker threads, this function stops the current thread rather
than the current process.
@since ― v0.1.13
@param ― code The exit code. For string type, only integer strings (e.g.,'1') are allowed.
Represents the completion of an asynchronous operation
Promise<
typeValueSource={
name:string;
value:unknown;
}
ValueSource[]>;
step.model holds the parameters declared before the checkpoint. resume() takes a list of value sources, the same shape as the values you pass to parse(). See Value and environment sources.
Command-line input survives the pause, so a flag still beats the loaded file. With a config.yml of { pr: { list: { limit: 50 } } }:
With a checkpoint at the root, parse() returns a step for every input, including --help, --version, and input that will fail. Help, version, and errors appear only after you resume:
gh --help pr list
→ a step at /, with configDir resolved
→ load the configuration and resume
→ HELP /pr/list
The router cannot produce a help or version intent until it knows the deepest route, and a later phase may add that route or its options. Do not inspect argv to skip a checkpoint. Make the I/O safe for help, version, and execute alike, and run side effects only after you receive an execute intent.
Calls a defined callback function on each element of an array, and returns an array that contains the results.
@param ― callbackfn A function that accepts up to three arguments. The map method calls the callbackfn function one time for each element in the array.
@param ― thisArg An object to which the this keyword can refer in the callbackfn function. If thisArg is omitted, undefined is used as the this value.
The process.argv property returns an array containing the command-line
arguments passed when the Node.js process was launched. The first element will
be
execPath
. See process.argv0 if access to the original value
of argv[0] is needed. The second element will be the path to the JavaScript
file being executed. The remaining elements will be any additional command-line
arguments.
For example, assuming the following script for process-args.js:
Returns a copy of a section of an array.
For both start and end, a negative index can be used to indicate an offset from the end of the array.
For example, -2 refers to the second to last element of the array.
@param ― start The beginning index of the specified portion of the array.
If start is undefined, then the slice begins at index 0.
@param ― end The end index of the specified portion of the array. This is exclusive of the element at the index 'end'.
If end is undefined, then the slice extends to the end of the array.
The console module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.
The module exports two specific components:
A Console class with methods such as console.log(), console.error() and console.warn() that can be used to write to any Node.js stream.
A global console instance configured to write to process.stdout and
process.stderr. The global console can be used without importing the node:console module.
Warning: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the note on process I/O for
more information.
Example using the global console:
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s','world');
// Prints: hello world, to stdout
console.error(newError('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
// Error: Whoops, something bad happened
// at [eval]:5:15
// at Script.runInThisContext (node:vm:132:18)
// at Object.runInThisContext (node:vm:309:38)
// at node:internal/process/execution:77:19
// at [eval]-wrapper:6:22
// at evalScript (node:internal/process/execution:76:60)
// at node:internal/main/eval_string:23:3
constname='Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
Example using the Console class:
constout=getStreamSomehow();
consterr=getStreamSomehow();
constmyConsole=new console.Console(out, err);
myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s','world');
// Prints: hello world, to out
myConsole.error(newError('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err
Prints to stderr with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to printf(3)
(the arguments are all passed to util.format()).
constcode=5;
console.error('error #%d', code);
// Prints: error #5, to stderr
console.error('error', code);
// Prints: error 5, to stderr
If formatting elements (e.g. %d) are not found in the first string then
util.inspect() is called on each argument and the
resulting string values are concatenated. See util.format()
for more information.
NodeJS.Process.exit(code?: number | string |null): never
The process.exit() method instructs Node.js to terminate the process
synchronously with an exit status of code. If code is omitted, exit uses
either the 'success' code 0 or the value of process.exitCode if it has been
set. Node.js will not terminate until all the 'exit' event listeners are
called.
To exit with a 'failure' code:
import{ exit }from'node:process';
exit(1);
The shell that executed Node.js should see the exit code as 1.
Calling process.exit() will force the process to exit as quickly as possible
even if there are still asynchronous operations pending that have not yet
completed fully, including I/O operations to process.stdout and process.stderr.
In most situations, it is not actually necessary to call process.exit() explicitly. The Node.js process will exit on its own if there is no additionalwork pending in the event loop. The process.exitCode property can be set to
tell the process which exit code to use when the process exits gracefully.
For instance, the following example illustrates a misuse of the process.exit() method that could lead to data printed to stdout being
truncated and lost:
import{ exit }from'node:process';
// This is an example of what *not* to do:
if(someConditionNotMet()){
printUsageToStdout();
exit(1);
}
The reason this is problematic is because writes to process.stdout in Node.js
are sometimes asynchronous and may occur over multiple ticks of the Node.js
event loop. Calling process.exit(), however, forces the process to exit before those additional writes to stdout can be performed.
Rather than calling process.exit() directly, the code should set the process.exitCode and allow the process to exit naturally by avoiding
scheduling any additional work for the event loop:
import process from'node:process';
// How to properly set the exit code while letting
// the process exit gracefully.
if(someConditionNotMet()){
printUsageToStdout();
process.exitCode =1;
}
If it is necessary to terminate the Node.js process due to an error condition,
throwing an uncaught error and allowing the process to terminate accordingly
is safer than calling process.exit().
In Worker threads, this function stops the current thread rather
than the current process.
@since ― v0.1.13
@param ― code The exit code. For string type, only integer strings (e.g.,'1') are allowed.
Represents the completion of an asynchronous operation
Promise<string[]>;
The schema validates the value you pass to resume(), and its input type sets what resume() accepts. The extension receives the validated value and returns the elements to add. Wrap several elements in extend(). A bare command() is a type error.
With ["dash", "copilot"] installed:
Invocation
Result
gh dash
EXECUTE /dash
gh dash --help
HELP /dash
gh nope
unprocessable-content with unexpected: `nope`
Routes added by dynamic() exist only at runtime, so the result type does not list them. In 0.8.0, result.route is typed as the statically declared routes only. To branch on an added route, read it as a string:
Calls a defined callback function on each element of an array, and returns an array that contains the results.
@param ― callbackfn A function that accepts up to three arguments. The map method calls the callbackfn function one time for each element in the array.
@param ― thisArg An object to which the this keyword can refer in the callbackfn function. If thisArg is omitted, undefined is used as the this value.
The process.argv property returns an array containing the command-line
arguments passed when the Node.js process was launched. The first element will
be
execPath
. See process.argv0 if access to the original value
of argv[0] is needed. The second element will be the path to the JavaScript
file being executed. The remaining elements will be any additional command-line
arguments.
For example, assuming the following script for process-args.js:
Returns a copy of a section of an array.
For both start and end, a negative index can be used to indicate an offset from the end of the array.
For example, -2 refers to the second to last element of the array.
@param ― start The beginning index of the specified portion of the array.
If start is undefined, then the slice begins at index 0.
@param ― end The end index of the specified portion of the array. This is exclusive of the element at the index 'end'.
If end is undefined, then the slice extends to the end of the array.