callbag-filter

Callbag operator that conditionally lets data pass through

Usage no npm install needed!

<script type="module">
  import callbagFilter from 'https://cdn.skypack.dev/callbag-filter';
</script>

README

/**

  • callbag-filter
  • Callbag operator that conditionally lets data pass through. Works on either
  • pullable or listenable sources.
  • npm install callbag-filter
  • Example:
  • const fromIter = require('callbag-from-iter');

  • const iterate = require('callbag-iterate');

  • const filter = require('callbag-filter');

  • const source = filter(x => x % 2)(fromIter([1,2,3,4,5]));

  • iterate(x => console.log(x))(source); // 1

  •                                       // 3

  •                                       // 5

*/

const filter = condition => source => (start, sink) => { if (start !== 0) return; let talkback; source(0, (t, d) => { if (t === 0) { talkback = d; sink(t, d); } else if (t === 1) { if (condition(d)) sink(t, d); else talkback(1); } else sink(t, d); }); };

module.exports = filter;