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Create a readable stream which always streams the same value.
import constantStream from 'https://cdn.jsdelivr.net/gh/stdlib-js/streams-node-from-constant@deno/mod.js';You can also import the following named exports from the package:
import { factory, objectMode } from 'https://cdn.jsdelivr.net/gh/stdlib-js/streams-node-from-constant@deno/mod.js';Returns a readable stream which always streams the same value.
import inspectStream from 'https://cdn.jsdelivr.net/gh/stdlib-js/streams-node-inspect-sink@deno/mod.js';
var iStream;
var stream;
function log( chunk, i ) {
console.log( chunk.toString() );
if ( i === 10 ) {
stream.destroy();
}
}
stream = constantStream( 'beep' );
iStream = inspectStream( log );
stream.pipe( iStream );The function accepts the following options:
- objectMode: specifies whether a stream should operate in objectMode. Default:
false. - encoding: specifies how
Bufferobjects should be decoded tostrings. Default:null. - highWaterMark: specifies the maximum number of bytes to store in an internal buffer before pausing streaming.
- sep: separator used to join streamed data. This option is only applicable when a stream is not in objectMode. Default:
'\n'. - iter: number of iterations.
To set stream options,
var opts = {
'objectMode': true,
'encoding': 'utf8',
'highWaterMark': 64
};
var stream = constantStream( 'beep', opts );By default, the function returns a stream which streams an infinite number of values (i.e., the stream will never end). To limit the number of streamed values, set the iter option.
import inspectStream from 'https://cdn.jsdelivr.net/gh/stdlib-js/streams-node-inspect-sink@deno/mod.js';
function log( chunk ) {
console.log( chunk.toString() );
}
var opts = {
'iter': 10
};
var stream = constantStream( 'beep', opts );
var iStream = inspectStream( log );
stream.pipe( iStream );By default, when not operating in objectMode, a returned stream delineates streamed values using a newline character. To specify an alternative separator, set the sep option.
import inspectStream from 'https://cdn.jsdelivr.net/gh/stdlib-js/streams-node-inspect-sink@deno/mod.js';
function log( chunk ) {
console.log( chunk.toString() );
}
var opts = {
'iter': 10,
'sep': ','
};
var stream = constantStream( 'beep', opts );
var iStream = inspectStream( log );
stream.pipe( iStream );Returns a function for creating readable streams which always stream the same provided value.
var opts = {
'objectMode': true,
'encoding': 'utf8',
'highWaterMark': 64
};
var createStream = constantStream.factory( opts );If provided a value to stream, the returned function returns readable streams which always stream the same value.
var createStream = constantStream.factory( 'beep' );
var stream1 = createStream();
var stream2 = createStream();
// ...If not provided a value to stream, the returned function requires that a value be provided at each invocation.
var createStream = constantStream.factory();
var stream1 = createStream( 'beep' );
var stream2 = createStream( 'boop' );
// ...The method accepts the same options as constantStream().
This method is a convenience function to create streams which always operate in objectMode.
import inspectStream from 'https://cdn.jsdelivr.net/gh/stdlib-js/streams-node-inspect-sink@deno/mod.js';
function log( v ) {
console.log( v );
}
var value = {
'beep': 'boop'
};
var opts = {
'iter': 10
};
var stream = constantStream.objectMode( value, opts );
opts = {
'objectMode': true
};
var iStream = inspectStream( opts, log );
stream.pipe( iStream );This method accepts the same options as constantStream(); however, the method will always override the objectMode option in options.
- In binary mode, a provided
valuemust be astring,Buffer, orUint8Array. - In
objectMode,nullis a reserved value. If providednull, the returned stream will prematurely end. - If provided an
objectreference, thevalueis not copied. To avoid unwanted mutation, copy thevaluebefore creating a stream. - In older Node.js environments,
Uint8Arraycontents may be copied to a newBufferobject due to changes in the underlying Node.js APIs. - If the
factorymethod is provided only one argument and that argument is anobject(either empty or not containing any recognizedoptionsproperties), the method treats the argument as a value to be streamed, not as anoptionsargument.
import inspectStream from 'https://cdn.jsdelivr.net/gh/stdlib-js/streams-node-inspect-sink@deno/mod.js';
import constantStream from 'https://cdn.jsdelivr.net/gh/stdlib-js/streams-node-from-constant@deno/mod.js';
function log( v ) {
console.log( v.toString() );
}
var opts = {
'objectMode': true,
'iter': 10
};
var stream = constantStream( 3.14, opts );
opts = {
'objectMode': true
};
var iStream = inspectStream( opts, log );
stream.pipe( iStream );@stdlib/streams-node/from-array: create a readable stream from an array-like object.@stdlib/streams-node/from-iterator: create a readable stream from an iterator.
This package is part of stdlib, a standard library with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.
For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.
See LICENSE.
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