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    sse-transform

    1.0.0 • Public • Published

    sse-transform

    Build Status

    A transform stream for converting JavaScript objects or JSON streams into Server-Sent Events. Only known fields (including comments) are processed and all other fields are ignored.

    Default Mode

    In default mode JSON objects are delimited using CrLf (\r\n). Each encountered JSON object is parsed and transformed into SSE format. If a JSON object isn't able to be parsed an error event is emitted on the stream and no transform is performed.

    Basic Usage
    'use strict';
     
    var sse = require('sse-transform');
    var through = require('through2');
     
     
    var xform = sse();
     
    xform.pipe(through(function (chunk, encoding, done) {
        console.log(chunk.toString('utf8'));
        done();
    }));
     
    xform.write('{"data":"foo"}\r\n');
    xform.write('{"id":123,"data":"abc"}\r\n');
    xform.write('{"event":"myevent","data":"foo\\nbar"}\r\n');
    xform.write('{"event":"myevent2","data":"moo\\nmar"}\r\n');
    xform.end();
    Output
    data:foo
     
     
    id:123
    data:abc
     
     
    event:myevent
    data:foo
    data:bar
     
     
    event:myevent2
    data:moo
    data:mar
     
     

    Object Mode

    In object mode each field processed such that if it is a string, newline delimiting rules are applied and each newline results in a new field entry (see data fields below). If a non-string-literal is encountered, the value is JSON.stringified during transform.

    Basic Usage
    'use strict';
     
    var sse = require('sse-transform');
    var through = require('through2');
     
     
    var xform = sse({ objectMode: true });
     
    xform.pipe(through(function (chunk, encoding, done) {
        console.log(chunk.toString('utf8'));
        done();
    }));
     
    xform.write({ data: 'foo'});
    xform.write({ id:123, data: 'abc' });
    xform.write({ event: 'myevent', data: 'foo\nbar' });
    xform.write({ event: 'myevent2', data: 'moo\nmar' });
    xform.write({ event: 'myevent', data: { foo: true, bar: 123, baz: 'foo\nbar' }});
    xform.end();
    Output
    data:foo
     
     
    id:123
    data:abc
     
     
    event:myevent
    data:foo
    data:bar
     
     
    event:myevent2
    data:moo
    data:mar
     
     
    event:myevent
    data:{"foo":true,"bar":123,"baz":"foo\nbar"}
     
     

    Fields

    The JSON or JavaScript object written to the stream can contain any properties, but only the following will be consumed by sse-transform, any other being ignored.

    • event - An event can contain any character besides carriage return or line feed. If the value contains a carriage return or line feed, the value is split on that character and the first segment used as the value.

    • data - The data field can include any string, including strings with carriage returns and/or line feeds. If the string contains newline characters, the string is split and multiple data fields are written per the SSE specification.

    • id - An id can contain any character besides carriage return or line feed. If the value contains a carriage return or line feed, the value is split on that character and the first segment used as the value.

    • retry - Per the Mozilla docs: "The reconnection time to use when attempting to send the event. This must be an integer, specifying the reconnection time in milliseconds. If a non-integer value is specified, the field is ignored."

    • $comment - Setting this property to include a comment in the event (any line starting with :). Comments can be used for keep-alives, etc.

    Install

    npm i sse-transform

    DownloadsWeekly Downloads

    1

    Version

    1.0.0

    License

    ISC

    Last publish

    Collaborators

    • totherik