Adding some partial documentation. Fixing batching timeout
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Lewis Diamond
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README.md
95
README.md
@ -2,10 +2,13 @@
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**Dependency-free stream utils for Node.js**
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<sub>Released under the [MIT](https://git.lewis.id/strom/blob/master/LICENSE) license.</sub>
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<sub>Released under the [MIT](LICENSE) license.</sub>
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```sh
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yarn add strom // Name TBD
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yarn add stromjs
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```
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```sh
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npm add stromjs
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```
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## fromArray(array)
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@ -23,7 +26,7 @@ strom.fromArray(["a", "b"])
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## map(mapper, options)
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Return a `ReadWrite` stream that maps streamed chunks
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Returns a `ReadWrite` stream that maps streamed chunks
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| Param | Type | Description |
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| --- | --- | --- |
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@ -41,7 +44,7 @@ strom.fromArray(["a", "b"])
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## flatMap(mapper, options)
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Return a `ReadWrite` stream that flat maps streamed chunks
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Returns a `ReadWrite` stream that flat maps streamed chunks
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| Param | Type | Description |
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| --- | --- | --- |
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@ -59,7 +62,7 @@ strom.fromArray(["a", "AA"])
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## filter(predicate, options)
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Return a `ReadWrite` stream that filters out streamed chunks for which the predicate does not hold
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Returns a `ReadWrite` stream that filters out streamed chunks for which the predicate does not hold
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| Param | Type | Description |
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| --- | --- | --- |
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@ -76,7 +79,7 @@ strom.fromArray(["a", "b", "c"])
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## reduce(iteratee, initialValue, options)
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Return a `ReadWrite` stream that reduces streamed chunks down to a single value and yield that
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Returns a `ReadWrite` stream that reduces streamed chunks down to a single value and yield that
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value
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| Param | Type | Description |
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@ -97,7 +100,7 @@ strom.fromArray(["a", "b", "cc"])
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## split(separator)
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Return a `ReadWrite` stream that splits streamed chunks using the given separator
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Returns a `ReadWrite` stream that splits streamed chunks using the given separator
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| Param | Type | Description |
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| --- | --- | --- |
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@ -115,7 +118,7 @@ strom.fromArray(["a,b", "c,d"])
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## join(separator)
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Return a `ReadWrite` stream that joins streamed chunks using the given separator
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Returns a `ReadWrite` stream that joins streamed chunks using the given separator
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| Param | Type | Description |
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| --- | --- | --- |
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@ -132,7 +135,7 @@ strom.fromArray(["a", "b", "c"])
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## replace(searchValue, replaceValue)
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Return a `ReadWrite` stream that replaces occurrences of the given string or regular expression in
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Returns a `ReadWrite` stream that replaces occurrences of the given string or regular expression in
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the streamed chunks with the specified replacement string
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| Param | Type | Description |
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@ -151,7 +154,7 @@ strom.fromArray(["a1", "b22", "c333"])
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## parse()
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Return a `ReadWrite` stream that parses the streamed chunks as JSON
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Returns a `ReadWrite` stream that parses the streamed chunks as JSON
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```js
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strom.fromArray(['{ "a": "b" }'])
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@ -162,7 +165,7 @@ strom.fromArray(['{ "a": "b" }'])
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## stringify()
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Return a `ReadWrite` stream that stringifies the streamed chunks to JSON
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Returns a `ReadWrite` stream that stringifies the streamed chunks to JSON
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```js
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strom.fromArray([{ a: "b" }])
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@ -173,7 +176,7 @@ strom.fromArray([{ a: "b" }])
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## collect(options)
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Return a `ReadWrite` stream that collects streamed chunks into an array or buffer
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Returns a `ReadWrite` stream that collects streamed chunks into an array or buffer
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| Param | Type | Description |
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| --- | --- | --- |
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@ -189,7 +192,7 @@ strom.fromArray(["a", "b", "c"])
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## concat(streams)
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Return a `Readable` stream of readable streams concatenated together
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Returns a `Readable` stream of readable streams concatenated together
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| Param | Type | Description |
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| --- | --- | --- |
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@ -210,7 +213,7 @@ source2.push(null);
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## merge(streams)
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Return a `Readable` stream of readable streams merged together in chunk arrival order
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Returns a `Readable` stream of readable streams merged together in chunk arrival order
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| Param | Type | Description |
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| --- | --- | --- |
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@ -231,7 +234,7 @@ setTimeout(() => source2.push(null), 50);
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## duplex(writable, readable)
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Return a `Duplex` stream from a writable stream that is assumed to somehow, when written to,
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Returns a `Duplex` stream from a writable stream that is assumed to somehow, when written to,
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cause the given readable stream to yield chunks
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| Param | Type | Description |
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@ -249,7 +252,7 @@ strom.fromArray(["a", "b", "c"])
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## child(childProcess)
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Return a `Duplex` stream from a child process' stdin and stdout
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Returns a `Duplex` stream from a child process' stdin and stdout
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| Param | Type | Description |
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| --- | --- | --- |
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@ -265,7 +268,7 @@ strom.fromArray(["a", "b", "c"])
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## last(readable)
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Return a `Promise` resolving to the last streamed chunk of the given readable stream, after it has
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Returns a `Promise` resolving to the last streamed chunk of the given readable stream, after it has
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ended
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| Param | Type | Description |
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@ -280,3 +283,61 @@ let f = async () => {
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f();
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// c is printed out
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```
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## accumulator(flushStrategy, iteratee, options)
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TO BE DOCUMENTED
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## batch(batchSize, maxBatchAge, options)
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Returns a `Transform` stream which produces all incoming data in batches of size `batchSize`.
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| Param | Type | Description |
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| --- | --- | --- |
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| `batchSize` | `number` | Size of the batches to be produced |
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| `maxBatchAge` | `number` | Maximum number of milliseconds a message will be queued for. E.g. a batch will be produced before reaching `batchSize` if the first message queued is `maxBatchAge` ms old or more |
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| `options` | `TransformOptions` | Options passed down to the Transform object |
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```js
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strom.fromArray(["a", "b", "c", "d"])
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.pipe(strom.batch(3, 500))
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.pipe(process.stdout);
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// ["a","b","c"]
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// ["d"] //After 500ms
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```
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## compose(streams, errorCb, options)
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Returns a `Transform` stream which consists of all `streams` but behaves as a single stream. The returned stream can be piped into and from transparently.
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| Param | Type | Description |
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| --- | --- | --- |
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| `streams` | `Array` | Streams to be composed |
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| `errorCb` | `(err: Error) => void` | Function called when an error occurs in any of the streams |
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| `options` | `TransformOptions` | Options passed down to the Transform object |
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```js
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const composed = strom.compose([
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strom.split(),
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strom.map(data => data.trim()),
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strom.filter(str => !!str),
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strom.parse(),
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strom.flatMap(data => data),
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strom.stringify(),
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]);
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const data = ["[1,2,3] \n [4,5,6] ", "\n [7,8,9] \n\n"];
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strom.fromArray(data).pipe(composed).pipe(process.stdout);
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// 123456789
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```
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## demux(pipelineConstructor, demuxBy, options)
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TO BE DOCUMENTED
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## parallelMap(mapper, parallel, sleepTime, options)
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Returns a `Transform` stream which maps incoming data through the async mapper with the given parallelism.
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| Param | Type | Description | Default |
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| --- | --- | --- | --- |
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| `mapper` | `async (chunk: T, encoding: string) => R` | Mapper function, mapping each (chunk, encoding) to a new chunk (non-async will not be parallelized) | -- |
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| `parallel` | `number` | Number of concurrent executions of the mapper allowed | 10 |
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| `sleepTime` | `number` | Number of milliseconds to wait before testing if more messages can be processed | 1 |
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@ -2,7 +2,7 @@ import { Transform, TransformOptions } from "stream";
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export function batch(
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batchSize: number = 1000,
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maxBatchAge: number = 500,
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maxBatchAge: number = 0,
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options: TransformOptions = {},
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): Transform {
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let buffer: any[] = [];
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@ -23,7 +23,7 @@ export function batch(
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buffer.push(chunk);
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if (buffer.length === batchSize) {
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sendChunk(this);
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} else {
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} else if (maxBatchAge) {
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if (timer === null) {
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timer = setInterval(() => {
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sendChunk(this);
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@ -39,7 +39,7 @@ test.cb("batch() yields a batch after the timeout", t => {
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const expectedElements = [["a", "b"], ["c"], ["d"]];
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let i = 0;
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source
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.pipe(batch(3))
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.pipe(batch(3, 500))
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.on("data", (element: string[]) => {
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t.deepEqual(element, expectedElements[i]);
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i++;
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