139 lines
4.1 KiB
Markdown
139 lines
4.1 KiB
Markdown
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# thingies
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Useful TypeScript utilities. [__Documentation__](https://streamich.github.io/thingies).
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## Menu
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- `base64` — Base64 encoding end decoding functions for Node.js.
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---
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- `Cache` — implementation of local memory cache for database records. Can cache
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retrieved database records for few dozen seconds and has garbage collection logic
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which clears the memory of old items after some time.
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---
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- `Defer` — an inverted `Promise`, an object which allows you to imperatively
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control the behavior of a `Promise`.
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---
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- `hash` — a fast and simple utility, which hashes a string to an integer. Useful
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for generating a shard index of a record based on its ID.
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---
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- `LruMap` — tiny and fast *Least Recently Used Cache* implemented on top of the `Map` class.
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---
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- `LruTtlMap` — tiny and fast *Least Recently Used Cache* with expiration timestamp
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stored for each entry implemented on top of the `LruMap` class.
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---
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- `normalizeEmail` — normalizes email by stripping out `.` and `+` characters and
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removing everything after the `+` character and lower-casing the e-mail. Useful for
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getting an e-mail into a common form when throttling requests by e-mail.
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---
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- `of` — returns result of a `Promise` as a 3-tuple `[value, error, isError]`.
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---
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- `promiseMap` — maps a list of values to an async function and waits until
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all results complete execution.
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---
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- `randomStr` — generates a random string of given size. Alphabet for character
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picking can be provided. Useful for generating random database record IDs.
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---
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- `TimedQueue` — a queue which can be flushed manually, or which flushes
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automatically when the number of queued items reaches a threshold or when a timeout
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expires since the first item was added to the queue. Useful for batching multiple
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messages or requests for bulk processing.
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---
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- `TimedState` — works similar to `TimedQueue`, but instead of keeping track of
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all items pushed, it invokes a reducer to update the state with the information from
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the last pushed item.
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---
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- `tick` — returns a `Promise` which resolves after a given number of milliseconds,
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useful for releasing the event loop for a short period of time, `await tick(5)`.
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---
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- `until` — waits for some condition to become true `await until(() => condition)`,
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useful when waiting for some asynchronous task to happen in a test.
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---
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- `concurrency` — limits the number of concurrent executions of asynchronous
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code. `concurrencyDecorator` limits the number of concurrent executions of a
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class method.
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---
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- `codeMutex` — a mutex which can be used to synchronize code execution. Code
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wrapped by this mutex will execute only one at a time, for all parallel calls to
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the same mutex.
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- `@mutex` and `mutex()` — same as `codeMutex`, but can be used as a decorator
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or a higher order function.
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---
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- `once` — a class method decorator, which limits method execution to once
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per instance. Returns the result of the first execution for all subsequent calls.
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---
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- `loadCss` — loads a CSS file into the DOM, given a URL. Does nothing on the
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server.
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---
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- `dataUri` — converts a string to a data URI.
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---
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- `FanOut` — a class which allows to fan out a single event to multiple
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listeners. Useful for implementing event emitters. In just 12 lines of code.
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---
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- `createRace` — constructs a "race" function, which takes a function as
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a single argument, the function is executed immediately only if no other
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function is currently executing. If another function is currently executing,
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the current function is discarded.
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---
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- `xorShift32` — generates random 32-bit integers using the very fast xorshift
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algorithm. `makeXorShift32(seed)` returns a function which can be used to generate
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random numbers.
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---
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- `Locks` — a lock manager, which allows to acquire an exclusive lock in
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browser across multiple tabs. Acquires a lock by writing to `localStorage` for
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a specific key for a specified duration.
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---
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- `hasKeys` — returns `true` if an object has at lest on key.
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## License
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[MIT © Vadim Dalecky](LICENSE).
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