Writable stream for inspecting streamed data.
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> [Writable stream][writable-stream] for inspecting streamed data.
``bash`
npm install @stdlib/streams-node-inspect-sink
`javascript`
var inspectSinkStream = require( '@stdlib/streams-node-inspect-sink' );
#### inspectSinkStream( \[options,] clbk )
Creates a [writable stream][writable-stream] for inspecting streamed data.
`javascript
function log( chunk, idx ) {
console.log( 'index: %d', idx );
console.log( chunk );
}
var stream = inspectSinkStream( log );
stream.write( 'a' );
stream.write( 'b' );
stream.write( 'c' );
stream.end();
// prints: index: 0
// prints: a
// prints: index: 1
// prints: b
// prints: index: 2
// prints: c
`
The function accepts the following options:
- objectMode: specifies whether a [stream][stream] should operate in [objectMode][object-mode]. Default: false.Buffer
- highWaterMark: specifies the level at which write() calls start returning false.Buffer
- decodeStrings: specifies whether to encode strings as objects before writing data to a returned [stream][stream]. Default: true.'utf8'
- defaultEncoding: default encoding when not explicitly specified when writing data. Default: .
To set [stream][stream] options,
`javascript
function log( chunk, idx ) {
console.log( 'index: %d', idx );
console.log( chunk );
}
var opts = {
'objectMode': true,
'highWaterMark': 64,
'decodeStrings': false,
'defaultEncoding': 'utf8'
};
var stream = inspectSinkStream( opts, log );
`
#### inspectSinkStream.factory( \[options] )
Returns a function for creating [streams][writable-stream] which are identically configured according to provided options.
`javascript
var opts = {
'objectMode': true,
'highWaterMark': 64
};
var factory = inspectSinkStream.factory( opts );
`
This method accepts the same options as inspectSinkStream().
##### factory( clbk )
Creates a [writable stream][writable-stream] for inspecting streamed data.
`javascript
function log( chunk, idx ) {
console.log( 'index: %d', idx );
console.log( chunk );
}
var factory = inspectSinkStream.factory();
// Create 10 identically configured streams...
var streams = [];
var i;
for ( i = 0; i < 10; i++ ) {
streams.push( factory( log ) );
}
`
#### inspectSinkStream.objectMode( \[options,] clbk )
This method is a convenience function to create [streams][stream] which always operate in [objectMode][object-mode].
`javascript
function log( chunk, idx ) {
console.log( 'index: %d', idx );
console.log( chunk );
}
var stream = inspectSinkStream.objectMode( log );
stream.write( { 'value': 'a' } );
stream.write( { 'value': 'b' } );
stream.write( { 'value': 'c' } );
stream.end();
// prints: index: 0
// prints: {'value': 'a'}
// prints: index: 1
// prints: {'value': 'b'}
// prints: index: 2
// prints: {'value': 'c'}
`
This method accepts the same options as inspectSinkStream(); however, the method will always override the [objectMode][object-mode] option in options.
`javascript
var parseJSON = require( '@stdlib/utils-parse-json' );
var transformFactory = require( '@stdlib/streams-node-transform' ).factory;
var inspect = require( '@stdlib/streams-node-inspect-sink' ).objectMode;
function parse( chunk, enc, clbk ) {
clbk( null, parseJSON( chunk ) );
}
function pluck( chunk, enc, clbk ) {
clbk( null, chunk.value );
}
function square( chunk, enc, clbk ) {
var v = +chunk;
clbk( null, v*v );
}
function toStr( chunk, enc, clbk ) {
clbk( null, chunk.toString() );
}
function join( chunk, enc, clbk ) {
clbk( null, chunk+'\n' );
}
function logger( chunk, idx ) {
console.log( 'index: %d', idx );
console.log( chunk );
}
// Create a factory for generating streams running in objectMode:
var tStream = transformFactory({
'objectMode': true
});
// Create streams for each transform:
var s1 = tStream( parse );
var s2 = tStream( pluck );
var s3 = tStream( square );
var s4 = tStream( toStr );
var s5 = tStream( join );
// Create a writable stream for inspecting the result of the transformations:
var is = inspect( logger );
// Create the pipeline:
s1.pipe( s2 )
.pipe( s3 )
.pipe( s4 )
.pipe( s5 )
.pipe( is );
// Write data to the pipeline...
var v;
var i;
for ( i = 0; i < 100; i++ ) {
v = '{"value":'+i+'}';
s1.write( v, 'utf8' );
}
s1.end();
`
*
- [@stdlib/streams-node/debug-sink][@stdlib/streams/node/debug-sink]: writable stream for debugging stream pipelines.
- [@stdlib/streams-node/inspect][@stdlib/streams/node/inspect]: transform stream for inspecting streamed data.
*
This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, 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][stdlib], see the main project [repository][stdlib].
#### Community
[![Chat][chat-image]][chat-url]
---
See [LICENSE][stdlib-license].
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
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[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules
[deno-url]: https://github.com/stdlib-js/streams-node-inspect-sink/tree/deno
[deno-readme]: https://github.com/stdlib-js/streams-node-inspect-sink/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/streams-node-inspect-sink/tree/umd
[umd-readme]: https://github.com/stdlib-js/streams-node-inspect-sink/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/streams-node-inspect-sink/tree/esm
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[branches-url]: https://github.com/stdlib-js/streams-node-inspect-sink/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/streams-node-inspect-sink/main/LICENSE
[stream]: https://nodejs.org/api/stream.html
[object-mode]: https://nodejs.org/api/stream.html#stream_object_mode
[writable-stream]: https://nodejs.org/api/stream.html
[@stdlib/streams/node/debug-sink]: https://www.npmjs.com/package/@stdlib/streams-node-debug-sink
[@stdlib/streams/node/inspect]: https://www.npmjs.com/package/@stdlib/streams-node-inspect