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How to use the concat function from rxjs

Find comprehensive JavaScript rxjs.concat code examples handpicked from public code repositorys.

rxjs.concat is a method in the RxJS library that combines multiple observables into a single observable that emits their values in order.

cloudStorageDownload.js

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do$(
    `download: ${JSON.stringify({bucketPath, prefix, downloadDir, deleteAfterDownload})}`,
    bucket.getFiles({prefix, autoPaginate: true})
).pipe(
    map(response => response[0]),
    switchMap(files => concat(
        of(getProgress({files})),
        downloadFiles$({files, prefix, downloadDir, deleteAfterDownload})
    ))
)

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pool.js

GitHub: openforis/sepal

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return {
    getInstance$: () =>
        getInstance$().pipe(
            switchMap(instance =>
                concat(of(instance), NEVER).pipe(
                    tap(instance => lock(instance)),
                    map(({item}) => item),
                    finalize(() => release(instance))
                )

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How does rxjs.concat work?

rxjs.concat is a method in the RxJS library that takes one or more observables as arguments and combines them into a single observable that emits their values in order. When you call rxjs.concat(obs1, obs2, ...), rxjs subscribes to obs1 and emits its values as they arrive. Once obs1 completes (i.e., emits a "complete" signal), rxjs subscribes to obs2 and emits its values in the same way, and so on for any additional observables. The resulting observable emits each value as it arrives, in the order of the original observables. If any observable throws an error, rxjs stops emitting values and propagates the error to its subscribers. rxjs.concat is useful when you need to combine multiple observables into a single stream, and you need to ensure that the values are emitted in a specific order. For example, you might use rxjs.concat to sequence API requests or database queries, or to ensure that certain events always happen in a particular order. Note that rxjs.concat is a "cold" observable, meaning that it does not start emitting values until a subscriber subscribes to it. If you need to combine observables that are already "hot" (i.e., emitting values), you might need to use a different method, such as rxjs.merge. Overall, rxjs.concat provides a flexible and powerful way to combine multiple observables into a single stream, allowing you to control the order of the emitted values and handle errors in a predictable way.

taskRunner.js

GitHub: openforis/sepal

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    of(initialState),
    progressState$.pipe(
        takeUntil(cancel$.pipe(
            tap(() => finalState$.next(cancelState))
        )),
        catchError(e => concat(finalize$, throwError(() => e)))
    ),
    finalize$,
    finalState$.pipe(first())
)

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+ 3 other calls in file

ws.js

GitHub: openforis/sepal

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        takeWhile(() => state.enabled)
    )

trigger$.pipe(
    switchMap(trigger =>
        concat(triggerAction$(trigger), poll$)
    ),
    exhaustMap(() => from(scanDirs())),
    distinctUntilChanged(_.isEqual),
    takeUntil(stop$),

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Ai Example

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const { of, concat } = require("rxjs");

// Create two observables that emit some values
const obs1 = of(1, 2, 3);
const obs2 = of(4, 5, 6);

// Combine the observables using concat
const combinedObs = concat(obs1, obs2);

// Subscribe to the combined observable and log its values
combinedObs.subscribe(
  (value) => console.log(value),
  (error) => console.error(error),
  () => console.log("Complete!")
);

In this example, we first import the of and concat operators from the rxjs library. We then create two observables (obs1 and obs2) using the of operator, which emits a sequence of values as separate emissions. We then use the rxjs.concat operator to combine the two observables into a single observable (combinedObs). rxjs.concat subscribes to obs1 and emits its values, and then subscribes to obs2 and emits its values, all in order. Finally, we subscribe to combinedObs and log its values to the console as they arrive. When the observable completes (i.e., when it emits a "complete" signal), we log "Complete!" to the console as well. The output of this example should be: Copy code

tracks.js

GitHub: feugy/melodie

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  { recordsMap: new Map(), records: [] }
),
mergeMap(({ records }) =>
  from(model.save(records)).pipe(
    mergeMap(({ saved, removedIds }) =>
      concat(
        from(saved).pipe(
          tap(record =>
            messages$.next({ type: `${property}-changes`, data: record })
          )

index.js

GitHub: caosbad/api

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exports.UnsubscriptionError = rxjs.UnsubscriptionError;
exports.TimeoutError = rxjs.TimeoutError;
exports.bindCallback = rxjs.bindCallback;
exports.bindNodeCallback = rxjs.bindNodeCallback;
exports.combineLatest = rxjs.combineLatest;
exports.concat = rxjs.concat;
exports.defer = rxjs.defer;
exports.empty = rxjs.empty;
exports.forkJoin = rxjs.forkJoin;
exports.from = rxjs.from;

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strategy.js

GitHub: kuldeepbait/AngClass

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function serialize() {
    let latest = rxjs_1.of();
    return (handler, options) => {
        const newHandler = (argument, context) => {
            const previous = latest;
            latest = rxjs_1.concat(previous.pipe(operators_1.ignoreElements()), new rxjs_1.Observable(o => handler(argument, context).subscribe(o))).pipe(operators_1.shareReplay(0));
            return latest;
        };
        return Object.assign(newHandler, {
            jobDescription: Object.assign({}, handler.jobDescription, options),

main.js

GitHub: dav793/node-postgres-csv-data-import

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        })
    );
});

return concat(...tasks).pipe(
    reduce((acc, cur) => acc.concat(cur), []),
    tap(res => {
        console.log(`Se procesaron ${res.length} entradas...`);
        continueReading$.next();

host.js

GitHub: SumeetOutlook/sumeet-practice

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        }
        catch (e) {
            obs.error(e);
        }
    });
    return rxjs_1.concat(...dirPaths.map(name => this.delete(src_1.join(path, name))), rmDirComplete);
}
else {
    try {
        fs.unlinkSync(src_1.getSystemPath(path));

+ 3 other calls in file

visitor.js

GitHub: SumeetOutlook/sumeet-practice

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    return rxjs_1.concat(rxjs_1.from(value).pipe(operators_1.mergeMap((item, i) => {
        return _visitJsonRecursive(item, visitor, pointer_1.joinJsonPointer(ptr, '' + i), _getObjectSubSchema(schema, '' + i), refResolver, context, root || value).pipe(operators_1.tap(x => (value[i] = x)));
    }), operators_1.ignoreElements()), rxjs_1.of(value));
}
else if (typeof value == 'object' && value !== null) {
    return rxjs_1.concat(rxjs_1.from(Object.getOwnPropertyNames(value)).pipe(operators_1.mergeMap(key => {
        return _visitJsonRecursive(value[key], visitor, pointer_1.joinJsonPointer(ptr, key), _getObjectSubSchema(schema, key), refResolver, context, root || value).pipe(operators_1.tap(x => {
            const descriptor = Object.getOwnPropertyDescriptor(value, key);
            if (descriptor && descriptor.writable && value[key] !== x) {
                value[key] = x;

+ 3 other calls in file

simple-scheduler.js

GitHub: SumeetOutlook/sumeet-practice

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 *
 * @param name The name of the job.
 * @returns A description, or null if the job is not registered.
 */
getDescription(name) {
    return rxjs_1.concat(this._getInternalDescription(name).pipe(operators_1.map(x => x && x.jobDescription)), rxjs_1.of(null)).pipe(operators_1.first());
}
/**
 * Returns true if the job name has been registered.
 * @param name The name of the job.

+ 2 other calls in file

record.js

GitHub: saleem1989/SalotimeMini

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            }
        }));
    }
}
rename(from, to) {
    return rxjs_1.concat(this.exists(to), this.exists(from)).pipe(operators_1.toArray(), operators_1.switchMap(([existTo, existFrom]) => {
        if (!existFrom) {
            return rxjs_1.throwError(new exception_1.FileDoesNotExistException(from));
        }
        if (from === to) {

+ 8 other calls in file

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