map-visit    

Map visit over an array of objects.

Install

Install with npm:

sh
$ npm install --save map-visit

Usage

js
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):

js
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).

js
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

• collection-visit: Visit a method over the items in an object, or map visit over the objects… more | [homepage](https://github.com/jonschlinkert/collection-visit "Visit a method over the items in an object, or map visit over the objects in an array.")
• object-visit: Call a specified method on each value in the given object. | [homepage](https://github.com/jonschlinkert/object-visit "Call a specified method on each value in the given object.")

Contributing

Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).

Contributors

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](.verb.md) readme template.)_

To generate the readme, run the following command:

sh
$ 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:

sh
$ npm install && npm test

Author

Jon Schlinkert

• github/jonschlinkert
• twitter/jonschlinkert

License

Copyright © 2017, Jon Schlinkert. Released under the [MIT License](LICENSE).

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