get-certain

sole-entry

Assert a Map has a given key and return the value for it.

Pretty much just map.get(key), but throws if key isn't there.

Install

$ yarn add get-certain

Usage

const getCertain = require('get-certain');
 
const map = new Map();
 
map.set('foo', 1);
 
// Returns 1.
getCertain(map, 'foo');
 
// This throws.
getCertain(map, 'bar');
 
// This throws with a custom message.
getCertain(map, 'bar', 'This map is barless.');

API

getCertain(map, key, [message])

Returns the value from map for key, or throws if it is not there.

map

• Type: Map

A Map. I hope you know what you're putting in there.

key

• Type: any

A key that is hopefully in map.

message

• Type: string

An optional message to throw. Defaults to '"map" does not have an entry for "key".', which isn't terribly descriptive.

License

MIT © Matthew Fernando Garcia