How to filter a Map based on a condition in Typescript?

In TypeScript, you can filter a Map based on a condition using the Map’s built-in methods along with some of JavaScript’s array methods. Since Map is iterable, you can convert it to an array, apply the filter, and then convert it back to a Map. Here’s how you can do it:

Example: Filtering a `Map`

Suppose you have a Map where the keys are strings and the values are numbers, and you want to filter out entries where the value is less than 50.

Here’s a step-by-step approach:

Create the Map:

const myMap = new Map<string, number>([
  ['a', 10],
  ['b', 60],
  ['c', 40],
  ['d', 90]
]);

Convert Map to an Array: Convert the Map to an array of entries using Array.from() or the spread operator [...].

const entriesArray = Array.from(myMap.entries());
// or
// const entriesArray = [...myMap.entries()];

Filter the Array: Use the filter method to filter the entries based on your condition.

const filteredEntries = entriesArray.filter(([key, value]) => value >= 50);

Convert the Filtered Array back to a Map: Convert the filtered array back to a Map.
```
const filteredMap = new Map<string, number>(filteredEntries);
```

Putting It All Together:

const myMap = new Map<string, number>([
  ['a', 10],
  ['b', 60],
  ['c', 40],
  ['d', 90]
]);

// Convert Map to Array of entries
const entriesArray = Array.from(myMap.entries());

// Filter the array based on a condition
const filteredEntries = entriesArray.filter(([key, value]) => value >= 50);

// Convert the filtered entries back to a Map
const filteredMap = new Map<string, number>(filteredEntries);

console.log(filteredMap); // Map { 'b' => 60, 'd' => 90 }