Function immutable

immutable<K, V>(
dataOrMap?: ReadonlyMap<K, V> | EitherKey<K, V>,
): IMapImmutable<K, V>

Returns an IMapImmutable. Use Maps.mutable as a mutable alternatve.

Type Parameters

Parameters

OptionaldataOrMap: ReadonlyMap<K, V> | EitherKey<K, V>
Optional initial data in the form of an array of { key: value } or [ key, value ]

Returns IMapImmutable<K, V>

Example: Basic usage

// Creating
let m = map();
// Add
m = m.set("name", "sally");
// Recall
m.get("name");

Example: Enumerating

for (const [key, value] of map.entries()) {
 console.log(`${key} = ${value}`);
}

Example: Overview

// Create
let m = map();
// Add as array or key & value pair
m = m.add(["name" , "sally"]);
m = m.add({ key: "name", value: "sally" });
// Add using the more typical set
m = m.set("name", "sally");
m.get("name");   // "sally";
m.has("age");    // false
m.has("name");   // true
m.isEmpty;       // false
m = m.delete("name");
m.entries();     // Iterator of key value pairs

Since it is immutable, add(), delete() and clear() return a new version with change.