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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](LICENSE).


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