map-visit

What is map-visit?

The map-visit npm package is designed to map over the properties of an object and apply a function to each property's value. It is particularly useful for manipulating and transforming object properties in a flexible and customizable way.

What are map-visit's main functionalities?

Mapping over object properties

This feature allows you to iterate over each property of an object and apply a function to its value. In the provided code sample, the function converts each property value to uppercase and logs it along with its key.

const mapVisit = require('map-visit');
const obj = { a: 'foo', b: 'bar' };
mapVisit(obj, (value, key) => console.log(key, value.toUpperCase()));

Other packages similar to map-visit

object-map

Similar to map-visit, object-map allows mapping over an object's properties to transform their values. However, object-map returns a new object with the transformed properties, whereas map-visit applies a function for side effects without necessarily returning a result.

map-obj

map-obj is another package that provides functionality to map keys and values of an object. Unlike map-visit, which is used for applying functions to object properties primarily for side effects, map-obj focuses on transforming the keys and values and returning a new object, which can be useful for more functional programming approaches.

README

map-visit

Map visit over an array of objects.

Install

Install with npm

$ npm i map-visit --save

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

Related projects

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

Running tests

Install dev dependencies:

$ npm i -d && npm test

Contributing

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

Author

Jon Schlinkert

• github/jonschlinkert
• twitter/jonschlinkert

License

Copyright © 2015 Jon Schlinkert Released under the MIT license.

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This file was generated by verb-cli on October 06, 2015.