Numerous Problems Multiplied

    map-visit

    1.0.0 • Public • Published

    map-visit NPM version NPM monthly downloads NPM total downloads Linux Build Status

    Map visit over an array of objects.

    Install

    Install with npm:

    $ npm install --save map-visit

    Usage

    var mapVisit = require('map-visit');

    What does this do?

    Assign/Merge/Extend vs. Visit

    Let's say you want to add a set method to your application that will:

    • set key-value pairs on a data object
    • extend objects onto the data object
    • extend arrays of objects onto the data object

    Example using extend

    Here is one way to accomplish this using Lo-Dash's extend (comparable to Object.assign):

    var _ = require('lodash');
     
    var obj = {
      data: {},
      set: function (key, value) {
        if (Array.isArray(key)) {
          _.extend.apply(_, [obj.data].concat(key));
        } else if (typeof key === 'object') {
          _.extend(obj.data, key);
        } else {
          obj.data[key] = value;
        }
      }
    };
     
    obj.set('a', 'a');
    obj.set([{b: 'b'}, {c: 'c'}]);
    obj.set({d: {e: 'f'}});
     
    console.log(obj.data);
    //=> {a: 'a', b: 'b', c: 'c', d: { e: 'f' }}

    The above approach works fine for most use cases. However, if you also want to emit an event each time a property is added to the data object, or you want more control over what happens as the object is extended, a better approach would be to use visit.

    Example using visit

    In this approach:

    • when an array is passed to set, the mapVisit library calls the set method on each object in the array.
    • when an object is passed, visit calls set on each property in the object.

    As a result, the data event will be emitted every time a property is added to data (events are just an example, you can use this approach to perform any necessary logic every time the method is called).

    var mapVisit = require('map-visit');
    var visit = require('object-visit');
     
    var obj = {
      data: {},
      set: function (key, value) {
        if (Array.isArray(key)) {
          mapVisit(obj, 'set', key);
        } else if (typeof key === 'object') {
          visit(obj, 'set', key);
        } else {
          // simulate an event-emitter
          console.log('emit', key, value);
          obj.data[key] = value;
        }
      }
    };
     
    obj.set('a', 'a');
    obj.set([{b: 'b'}, {c: 'c'}]);
    obj.set({d: {e: 'f'}});
    obj.set({g: 'h', i: 'j', k: 'l'});
     
    console.log(obj.data);
    //=> {a: 'a', b: 'b', c: 'c', d: { e: 'f' }, g: 'h', i: 'j', k: 'l'}
     
    // events would look something like:
    // emit a a
    // emit b b
    // emit c c
    // emit d { e: 'f' }
    // emit g h
    // emit i j
    // emit k l

    About

    Related projects

    Contributing

    Pull requests and stars are always welcome. For bugs and feature requests, please create an issue.

    Contributors

    Commits Contributor
    15 jonschlinkert
    7 doowb

    Building docs

    (This project's readme.md is generated by verb, please don't edit the readme directly. Any changes to the readme must be made in the .verb.md readme template.)

    To generate the readme, run the following command:

    $ npm install -g verbose/verb#dev verb-generate-readme && verb

    Running tests

    Running and reviewing unit tests is a great way to get familiarized with a library and its API. You can install dependencies and run tests with the following command:

    $ npm install && npm test

    Author

    Jon Schlinkert

    License

    Copyright © 2017, Jon Schlinkert. Released under the MIT License.


    This file was generated by verb-generate-readme, v0.5.0, on April 09, 2017.

    Install

    npm i map-visit

    DownloadsWeekly Downloads

    16,617,316

    Version

    1.0.0

    License

    MIT

    Last publish

    Collaborators

    • doowb
    • jonschlinkert