isResult<
T
,E
>(result
):result is Result<T, E>
Defined in: functions/is-result.ts:25
Type guard to check if a value is a Result.
T
The type of the success value.
E
The type of the error value.
unknown
The value to check.
result is Result<T, E>
true
if the value is a Result, otherwise false
.
import { import Result
Result } from '@praha/byethrow';
const const value: unknown
value : unknown = { type: string
type : 'Success', value: number
value : 42 };
if (import Result
Result .const isResult: <unknown, unknown>(result: unknown) => result is Result.Result<unknown, unknown>
Type guard to check if a value is a
Result
.
@function@typeParamT
- The type of the success value.@typeParamE
- The type of the error value.@paramresult
- The value to check.@returnstrue
if the value is a Result
, otherwise false
.@exampleimport { Result } from '@praha/byethrow';
const value: unknown = { type: 'Success', value: 42 };
if (Result.isResult(value)) {
// value is now typed as Result<unknown, unknown>
console.log(value.type); // 'Success' or 'Failure'
}
@categoryType
Guards isResult (const value: unknown
value )) {
// value is now typed as Result<unknown, unknown>
var console: Console
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(new Error('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
const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
Example using the Console
class:
const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = 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(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err
const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
@seesource console .Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)
Prints to stdout
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()
).
const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
See util.format()
for more information.
@sincev0
.1.100 log (const value: Result.Result<unknown, unknown>
value .type: "Success" | "Failure"
type ); // 'Success' or 'Failure'
}