map-visit

Map visit over an array of objects.

Install

Install with npm:

$ npm install --save map-visit

Usage

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

Assign or Merge 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:

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. But if you also want to emit an event each time a property is added to the data object. A better approach would be to use visit.

Example using visit

In this approach, when an array is passed to set, mapVisit calls set 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.

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 {
      // some 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

• collection-visit: Visit a method over the items in an object, or map visit over the objects… more | homepage
• object-visit: Call a specified method on each value in the given object. | homepage

Contributing

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

Building docs

(This document was generated by verb-generate-readme (a verb generator), please don't edit the readme directly. Any changes to the readme must be made in .verb.md.)

To generate the readme and API documentation with verb:

$ npm install -g verb verb-generate-readme && verb

Running tests

Install dev dependencies:

$ npm install -d && npm test

Author

Jon Schlinkert

• github/jonschlinkert
• twitter/jonschlinkert

License

Copyright © 2016, Jon Schlinkert. Released under the MIT license.

This file was generated by verb, v0.9.0, on August 05, 2016.