Pipes in Angular
⭐ What Are Pipes in Angular?
A Pipe in Angular is a tool used in templates to transform or format data before displaying it to the user.
You apply a pipe using the pipe symbol |.
Example:
Pipes help format:
Text
Dates
Numbers
Currency
JSON
Custom transformations
🎯 Why Use Pipes?
✔ For clean UI formatting
✔ To avoid writing logic inside the component
✔ To transform data directly inside templates
✔ To reuse formatting across the app
⭐ Built-in Angular Pipes
Here are the most common ones:
| Pipe | Example | Output |
|---|---|---|
uppercase | `{{ ‘hello’ | uppercase }}` |
lowercase | `{{ ‘HELLO’ | lowercase }}` |
titlecase | `{{ ‘hello world’ | titlecase }}` |
date | `{{ today | date:’short’ }}` |
currency | `{{ 500 | currency:’INR’ }}` |
percent | `{{ 0.25 | percent }}` |
json | Shows object as JSON | |
slice | `{{ arr | slice:1:3 }}` |
🧩 Example: Date Formatting
TS
HTML
Output example:
👉 Friday, December 12, 2025
🧩 Example: Currency Pipe
Output:
👉 ₹4,999.00
⭐ Using Multiple Pipes (Pipe Chaining)
You can apply more than one pipe:
Steps:
Convert to UPPERCASE → “HELLO WORLD”
Slice → “HELLO”
⭐ Pipes with Parameters
Some pipes accept arguments:
'1.2-2' → one digit before decimal, 2 minimum fraction digits, 2 max.
⭐ Pipes with Async Data (Async Pipe)
For Observables or Promises:
TS
HTML
Output:
👉 Sanjit
Async pipe:
Subscribes automatically
Unsubscribes when component is destroyed
⭐ JSON Pipe for Debugging
Helpful for displaying object data during development.
⭐ Custom Pipes
You can create your own pipe:
Create Pipe
Pipe Code
Use in Template
🔍 Rules of Pipes in Templates
✔ Pipes are pure by default → fast
✔ Called only when input changes
✔ Cannot modify original data
✔ They only transform values shown in the template
🎉 One-Line Summary
👉 Pipes (|) let you transform data in Angular templates—formatting text, numbers, dates, or custom logic easily.
