angular__angular/tools/manual_api_docs/blocks/let.md

@let allows you to define a local variable and re-use it across the template.

Syntax

@let name = user.name;
@let data = data$ | async;

Description

@let declarations are similar to JavaScript's let and their values can be any valid Angular expression. The expressions will be re-evaluated every time the template is executed.

Similarly to JavaScript variables, variables declared with @let, can be used:

• After they have been declared
• Within the bound of the same scope and nested scopes

@let user = user$ | async;

@if (user) {
  <h1>Hello, {{ user.name }}</h1>
  <user-avatar [photo]="user.photo" />

  <ul>
    @for (snack of user.favoriteSnacks; track snack.id) {
      <li>{{ snack.name }}</li>
    }
  </ul>

  <button (click)="update(user)">Update profile</button>
}

Syntax definition

The @let syntax is formally defined as:

• The @let keyword.
• Followed by one or more whitespaces, not including new lines.
• Followed by a valid JavaScript name and zero or more whitespaces.
• Followed by the = symbol and zero or more whitespaces.
• Followed by an Angular expression which can be multi-line.
• Terminated by the ; symbol.

HELPFUL: A comprehensive description of the feature is available on the templates guide