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feat(curriculum): Add interactive examples to Filter method lesson (#63399)
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@@ -5,12 +5,14 @@ challengeType: 19
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dashedName: what-is-the-filter-method-and-how-does-it-work
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---
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# --description--
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# --interactive--
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The `filter` method is used to create a new array with elements that pass a specified test, making it useful for selectively extracting items based on criteria.
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In this example, we are using the `filter` method, to create a new array of only even numbers:
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:::interactive_editor
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```js
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const numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
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const evenNumbers = numbers.filter((num) => num % 2 === 0);
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@@ -18,6 +20,8 @@ const evenNumbers = numbers.filter((num) => num % 2 === 0);
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console.log(evenNumbers); // [2, 4, 6, 8, 10]
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```
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:::
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In this example, the `filter` method applies a callback function to each element of the `numbers` array. The callback checks whether each number is even using the modulo operator (`%`).
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If the number is even, the function returns `true`, and that number is included in the new array. If it's odd, the function returns `false`, and that number is excluded.
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@@ -26,17 +30,23 @@ Just like the `map` method, the callback function for the `filter` method accept
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It's important to note that if no elements pass the test, the `filter` method returns an empty array.
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:::interactive_editor
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```js
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const numbers = [2, 4, 6, 8].filter((num) => num > 10);
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console.log(numbers); // []
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```
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:::
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`filter` is incredibly versatile and can be used in many scenarios. You can use it to remove `null` or `undefined` values from an array, to filter objects based on their properties, or to implement search functionality.
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Here's an example of using the `filter` method to return an array of objects for individuals younger than `30` years old.
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```javascript
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:::interactive_editor
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```js
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const developers = [
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{ name: "Alice", age: 25 },
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{ name: "Bob", age: 30 },
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@@ -50,6 +60,8 @@ console.log(youngPeople);
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// [{ name: "Alice", age: 25 }, { name: "David", age: 25 }]
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```
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:::
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Throughout the rest of this curriculum, you will be using the `map` and `filter` methods very frequently. So, building familiarity with them will not only streamline your coding process but also help you write cleaner and more efficient code.
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# --questions--
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