Interpolation In Angular

String interpolation, also known as text interpolation, in Angular refers to the process of binding a component class property to the template using double curly braces ({{ }}).

This allows dynamic data from the component to be displayed in the HTML view. When the property value changes in the component, the corresponding update is automatically reflected in the template. This is a form of one-way data binding — from the component class to the template.

{{expression}}

Where expression is usually a component property or a method call that returns a value.

Why Use Text Interpolation (or) Text Interpolation:

Text Interpolation HelpsYou to:

• Display Dynamic values like strings, numbers, or method outputs.
• Keep Your HTML Updated automatically when the component changes.
• Maintain a clean seperation between logic (Typescript) and UI (HTML).

What You can't do with Interpolation:

• You can’t use control structures like if, for, or while.
• You can’t assign values like {{ count = 10 }} — it must be a read-only expression.
• You can’t access DOM elements or global objects like document or window.

We can also assign an expression or value to a component property, where that expression may be computed or retrieved from an external, publicly accessible source (such as a service or constant). Once assigned, this property can be resolved and displayed in the template using interpolation with double curly braces ({{ }}).

If you were referring to using external variables directly in the template (without passing them through the component), that would not be technically correct in Angular. All data used inside interpolation must be accessible from the component’s class context.