data-collectors
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    1.0.5 • Public • Published

    Collectors

    A collection of composable reduction operations for arbitrary streams of values

    Installation

    npm install --save data-collectors

    Usage

    Useful to reduce data in many ways.

    import { collect, groupingBy, first, mapping, sorting } from 'data-collectors';
     
    interface Person {
        role : 'admin' | 'moderator' | 'user';
        id : number;
        name : string;
    }
     
    const array : Person[] = [ { role: 'admin', id: 1, name: 'John' }, { role: 'user', id: 2, name: 'David' }, { role: 'user', id: 3, name: 'Peter' } ];
     
    let collector = groupingBy( user => user.role, groupingBy( user => user.id, first() ) );
     
    collect( array, collector ); // Map { 'admin' => Map{ 1 => ... }, 'user' => { 2 => ..., 3 => ... } };
     
    let collector2 = groupingBy( user => user.role, mapping( user => user.id ) );
     
    collect( array, collector2 ); // Map { 'admin' => [ 1 ], 'user' => [ 2, 3 ] };
     
    // Sort the array by name
    collect( array, sorting( ( a, b ) => a.name.localeCompare( b.name ) ) );  // [ { ... name: 'David' }, { ... name: 'John' }, { ... name: 'Peter' } ]

    Note that while some collectors can only be used on their own (like first or last), others can be composed (like mapping accepts a second argument after the mapper function, or groupingBy which also accepts a second optional collector argument (default is toArray()) that will be applied to each value of the resulting Map).

    Install

    npm i data-collectors

    DownloadsWeekly Downloads

    23

    Version

    1.0.5

    License

    ISC

    Unpacked Size

    69.9 kB

    Total Files

    67

    Last publish

    Collaborators

    • pedromsilva