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Common API

In this documentation, we will focus on the common API. This module includes the core of BatchJS. This API allows you to create your own custom jobs and steps using the common interface.

Table of Contents

Job

abstract extends EventEmitter

Abstract base class for all jobs.

Examples

export class JobImplementation extends Job {
    protected _steps() {
        return [new PassingStepFirst(), new PassingStepSecond()];
    }
}

const job = new JobImplementation("My job");
job.on("stepStart", (step:step) => {
    console.log(`Starting step ${step.name}`);
})
job.run()
    .then(() => {
        console.log("Job completed successfully");
    })
    .catch((error) => {
        console.log("Job completed with errors");
    });
>> Starting step PassingStepFirst
>> Starting step PassingStepSecond
>> Job completed successfully

Constructor

Name Description Type
name The name to assign to the Step. string

_steps (function)

protected static abstract

Abstract method that most be implemented by the job in order to returns an ordered array of steps that make up the job.

Returns

Type Description
Array.<Step>

run (function)

Asynchronously runs the job by executing each step in sequence.

Returns

Type Description
Promise.<void> A Promise that resolves when all steps are successfully executed or rejects if an error occurs.

addListener (function)

Adds an event listener to the specified event type.

Parameters

Name Description Type
event start, end, stepStart, stepEnd
listener function

Returns

Type Description
this allowing to chain

emit (function)

Emits an event of the specified type to the listeners.

Parameters

Name Description Type
event start, end, stepStart, stepEnd
args Data to sent to the listeners depending on the event type Array.<JobEventEmitters>

Returns

Type Description
boolean

on (function)

Adds an event listener to the specified event type.

Parameters

Name Description Type
event start, end, stepStart, stepEnd
listener function

Returns

Type Description
this allowing to chain

once (function)

Adds a one time event listener to the specified event type.

Parameters

Name Description Type
event start, end, stepStart, stepEnd
listener function

Returns

Type Description
this allowing to chain

prependListener (function)

Adds an event listener to the specified event type to the beginning of the listeners array.

Parameters

Name Description Type
event start, end, stepStart, stepEnd
listener function

Returns

Type Description
this allowing to chain

prependOnceListener (function)

Adds a one time event listener to the specified event type to the beginning of the listeners array.

Parameters

Name Description Type
event start, end, stepStart, stepEnd
listener function

Returns

Type Description
this allowing to chain

removeListener (function)

Removes an event listener to the specified event type.

Parameters

Name Description Type
event start, end, stepStart, stepEnd
listener function

Returns

Type Description
this allowing to chain

Step

abstract

Abstract base class for all steps.

Examples

class StepImplementation extends Step {
    constructor(name: string = "MockPassingStep") {
        super(name);
    }

    protected _reader() {
        return new Readable({
            objectMode: true,
            read() {
                this.push("data");
                this.push(null);
            }
        });
    }

    protected _processors() {
        const opts: TransformOptions = {
            objectMode: true,
            transform(chunk: unknown, encoding: BufferEncoding, callback: TransformCallback) {
                this.push(chunk);
                callback();
            }
        };
        return [new Transform(opts), new Transform(opts)];
    }

    protected _writer() {
        return new Writable({
            objectMode: true,
            write(chunk: unknown, encoding: BufferEncoding, callback: TransformCallback) {
                callback();
            }
        });
    }
}
const step = new StepImplementation("StepImplementation");
step.run()
    .then(() => {
        console.log("Step completed successfully");
    })
    .catch((error) => {
        console.log("Step completed with errors");
    });
>> Step completed successfully

Constructor

Name Description Type
name The name to assign to the Step. string

_reader (function)

protected static abstract

Abstract method that must be implemented by the step in order to defined the reader stream.

Returns

Type Description
Readable

_processors (function)

protected static abstract

Abstract method that must be implemented by the step in order to process the data from the reader stream and push it to the writer stream. Processors are defined in an ordered array to be chained on the runner.

Returns

Type Description
Array.<Duplex>

_writer (function)

protected static abstract

Abstract method that must be implemented by the step in order to defined the writer stream.

Returns

Type Description
Writable

run (function)

Executes the step by connecting streams, processing data, and listening for events.

Returns

Type Description
Promise.<void> A Promise that resolves when the step execution is completed, and rejects if an error occurs.