https://github.com/isaacs/pseudomap

Like `new Map` but for older JavaScripts
https://github.com/isaacs/pseudomap

Last synced: 18 days ago
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Like `new Map` but for older JavaScripts

• Host: GitHub
• URL: https://github.com/isaacs/pseudomap
• Owner: isaacs
• License: isc
• Created: 2015-11-25T19:58:02.000Z (about 9 years ago)
• Default Branch: main
• Last Pushed: 2023-10-10T17:30:50.000Z (about 1 year ago)
• Last Synced: 2024-11-14T21:36:38.740Z (28 days ago)
• Language: JavaScript
• Size: 196 KB
• Stars: 21
• Watchers: 2
• Forks: 16
• Open Issues: 15
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# pseudomap

A thing that is a lot like ES6 `Map`, but without iterators, for use

in environments where `for..of` syntax and `Map` are not available.

[![Build Status](https://travis-ci.org/isaacs/pseudomap.svg?branch=master)](https://travis-ci.org/isaacs/pseudomap/) [![Coverage Status](https://coveralls.io/repos/isaacs/pseudomap/badge.svg?branch=master&service=github)](https://coveralls.io/github/isaacs/pseudomap?branch=master)

If you need iterators, or just in general a more faithful polyfill to

ES6 Maps, check out [es6-map](http://npm.im/es6-map).

If you are in an environment where `Map` is supported, then that will

be returned instead, unless `process.env.TEST_PSEUDOMAP` is set.

You can use any value as keys, and any value as data.  Setting again

with the identical key will overwrite the previous value.

Internally, data is stored on an `Object.create(null)` style object.

The key is coerced to a string to generate the key on the internal

data-bag object.  The original key used is stored along with the data.

In the event of a stringified-key collision, a new key is generated by

appending an increasing number to the stringified-key until finding

either the intended key or an empty spot.

Note that because object traversal order of plain objects is not

guaranteed to be identical to insertion order, the insertion order

guarantee of `Map.prototype.forEach` is not guaranteed in this

implementation.  However, in all versions of Node.js and V8 where this

module works, `forEach` does traverse data in insertion order.

## API

Most of the [Map

API](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map),

with the following exceptions:

1. A `Map` object is not an iterator.

2. `values`, `keys`, and `entries` methods are not implemented,

   because they return iterators.

3. The argument to the constructor can be an Array of `[key, value]`

   pairs, or a `Map` or `PseudoMap` object.  But, since iterators

   aren't used, passing any plain-old iterator won't initialize the

   map properly.

## USAGE

Use just like a regular ES6 Map.

```javascript

var PseudoMap = require('pseudomap')

// optionally provide a pseudomap, or an array of [key,value] pairs

// as the argument to initialize the map with

var myMap = new PseudoMap()

myMap.set(1, 'number 1')

myMap.set('1', 'string 1')

var akey = {}

var bkey = {}

myMap.set(akey, { some: 'data' })

myMap.set(bkey, { some: 'other data' })

```