Rxjs Operator 30: distinctUntilChanged Operator

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Rxjs Operator 29: debounceTime Operator

What is the distinctUntilChanged Operator and What Does It Do?

The distinctUntilChanged operator is used to filter out values in an observable stream that are identical to the immediately preceding value. It ensures that only new and distinct values are propagated downstream, while repeated or redundant values are ignored. Key features of the distinctUntilChanged operator include:

• Filtering Repeated Values: It eliminates values that are the same as the previous one, preventing redundant processing.
• Ensuring Uniqueness: It helps ensure that emitted values are unique and distinct, promoting data integrity.
• Operational Efficiency: It optimizes data processing by avoiding unnecessary operations on repeated values.

Let’s see a how to code, for this let’s implement search functionality that includes taking unique value and with some delay.

1. debounceTime(300):
2. The debounceTime operator is used to introduce a time delay between events before they are emitted. In the example, it ensures that there is a 300ms pause in typing before considering the input value for a search query. This delay helps in avoiding rapid and frequent emissions, ensuring that the search query is only sent after a brief inactivity period.
3. For instance, if a user types quickly, the operator will wait for 300ms of inactivity before emitting the most recent value. This prevents unnecessary searches during rapid typing and optimizes the user experience.
4. distinctUntilChanged():
5. The distinctUntilChanged operator ensures that the emitted value is distinct and different from the previous value. It is used in the example to filter out repeated values. In the context of search functionality, this operator ensures that a new search query is only triggered if it is different from the previous one.
6. For example, if a user deletes a character and retypes the same query, the operator prevents redundant searches by ignoring the repeated value. It’s particularly useful in scenarios where you want to avoid processing the same input multiple times and optimize performance.

Here’s how these operators work together:

• When a user types in the search input field, the input$ observable captures the input value and applies debounceTime(300) to wait for a pause in typing.
• distinctUntilChanged() ensures that only distinct search queries are considered. If a user rapidly types and deletes characters, the operator prevents redundant searches.
• The filter operator then checks that the search query is at least 3 characters long. This avoids searches for very short or empty queries.

These operators, used together, create a smooth and optimized search experience by waiting for a pause in typing and ensuring that only distinct, meaningful search queries are processed.

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Rxjs Operator 31: elementAt Operator

Stackblitz Link
https://stackblitz.com/edit/rxjs-operator-distinctuntilchanged

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