Jaco Greeff
b5c5734c7c
* Initial split of util & util-crypto * Add initial XXHash version * Blake2s wit tests & documentation * Add sha512 (from NaCl) * Add randomBytes (from NaCl) * Flow fixes * Update documentation * Update latest @polkadot/dev
70 lines
2.4 KiB
Markdown
70 lines
2.4 KiB
Markdown
# Available interfaces
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Utility methods for this package are split into groups
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- [array](array.md) Utility methods that operates on arrays
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- [bn](bn.md) Utility methods to convert to and from `BN` objects
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- [buffer](buffer.md) Utility methods to convert to and from `Buffer` objects
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- [ext](ext.md) Extensions to basic classes
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- [hex](hex.md) Internal utilities to create and test for hex values
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- [is](is.md) Type checking utilities
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- [jsonrpc](jsonrpc.md) Convenience functions for values from @polkadot/api-jsonrpc
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- [number](number.md) Utility methods to convert to and from `number` values
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- [string](string.md) Utility methods to convert to work with `string` values
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- [u8a](u8a.md) Utility methods to convert to and from `Uint8Array` objects
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# Available methods
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## assert
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Checks for a valid test, if not ExtError is thrown.
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```js
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assert (test: mixed, message: string | () => string, code: number = ExtError.CODES.ASSERT, data: mixed): void
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```
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Checks that `test` is a truthy value. If value is falsy (`null`, `undefined`, `false`, ...), it throws an ExtError with the supplied `message` and an optional `code` and `data`. When `test` passes, `true` is returned.
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```js
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const assert = require('@polkadot/util/assert');
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assert(true, 'True should be true'); // true returned
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assert(false, 'False should not be true'); // ExtError thrown
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assert(false, () => 'message'); // ExtError with 'message'
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```
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## Logger
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Creates a consistent log interface for messages
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```js
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logger (type: string): Logger
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```
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Returns a `Logger` that has `.log`, `.error`, `.warn` and `.debug` (constrolled with environment `DEBUG=typeA,typeB`) methods. Logging is done with a consistent prefix (type of logger, date) followed by the actual message using the underlying console.
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```js
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const l = require('@polkadot/util/logger')('test');
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l.log('blah'); // <date> TEST: blah
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```
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## promisify
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Wraps an async callback into a `Promise`
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```js
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function promisify (this: ?Object, fn: Function, ...params: Array<mixed>): Promise<any>
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```
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Wraps the supplied async function `fn` that has a standard JS callback `(error: Error, result: any)` into a `Promise`, passing the supplied parameters. When `error` is set, the Promise is rejected, else the Promise resolves with the `result` value.
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```js
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const promisify = require('@polkadot/util/promisify');
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await promisify(null, ((a, cb) => cb(null, a), true); // resolves with `true`
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await promisify(null, (cb) => cb(new Error('error!'))); // rejects with `error!`
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``` |