Angular templates support two kinds of variable declarations: @let for a local value derived from an expression, and #name for a reference to a template object such as an element, component, directive, or TemplateRef. Both are scoped to their template, so a nested block can use an outer variable, but a parent cannot access one declared only inside that block.
Choose the declaration that matches what you need
| Form | What it declares | Typical use |
|---|---|---|
@let name = expression; |
A local variable whose value comes from an Angular template expression and stays current as that expression changes. | Reuse an expression value in several places in a template. |
#name |
A reference to the object associated with the declaration site: usually an element, but potentially a component, directive, or TemplateRef. |
Refer to a template object, such as an input element or reusable template fragment. |
Declare a local value with @let
Use @let when you want to give a template expression a name. The declaration has the form @let name = expression; and must end with a semicolon. Each declaration creates exactly one variable.
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@let user = user$ | async;
@if (user) {
<h1>Hello, {{ user.name }}</h1>
<button (click)="update(user)">Update profile</button>
}Angular keeps the variable’s value in sync with its expression. It is not a mutable JavaScript local: do not try to assign a new value to the variable. The expression can span multiple lines, but the declaration still ends with a semicolon.
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Use #name to reference a template object
Put a reference variable on the element or template you want to identify. What the variable refers to depends on that host:
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- On a regular element, it refers to the element instance.
- On a component, it refers to the component instance.
- On an
<ng-template>, it refers to aTemplateRef. - On an element with a directive, it can refer to that directive’s instance if you specify a matching
exportAsname.
Reference an element
<input #taskInput placeholder="Enter task name" />Reference an exported directive
<section dropZone #firstZone="dropZone">...</section>This form requires the directive to declare exportAs: 'dropZone'. A directive without an exportAs name cannot be referenced this way.
Use a reference with a view query
A reference can identify a target for a component view query, for example @ViewChild('description'). The reference’s value still depends on the host where it was declared.
Understand template scope
Template variables are available in their declaring template and nested scopes. A child scope can read a variable declared in its parent, but a parent cannot reach into a child scope. @let declarations are not hoisted, so declare a variable in the scope where it is needed.
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@let topLevel = value;
@if (condition) {
{{ topLevel }}
@let nested = value;
{{ nested }}
}
<!-- `nested` is unavailable here because it was declared in the @if scope. -->The same rule applies to variables declared inside @for, structural directives, and <ng-template> scopes. A nested template can use an outer variable; the outer template cannot use a variable declared only inside the nested template.
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Do not confuse @let with let- template parameters
@let creates a local variable from an expression. By contrast, a let- attribute on an <ng-template> declares a parameter that receives a value from that template fragment’s context object.
<ng-template #fragment let-topping="topping">
<p>You selected: {{ topping }}</p>
</ng-template>
<ng-container
[ngTemplateOutlet]="fragment"
[ngTemplateOutletContext]="{ topping: 'onion' }" />Here, topping is supplied through the outlet context. The fragment remains associated with the component in which it was declared.
Watch for name shadowing
Angular template expressions can access the component context as well as relevant template variables and locals. If a template variable has the same name as a component member, the template variable takes precedence. Use this.member when you mean the component property explicitly.
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Common mistakes
- Trying to reassign a variable declared with
@let. - Using a variable outside the template scope where it was declared.
- Assuming every
#namerefers to a DOM element, regardless of its host. - Using
#ref="name"without a directive that exports the matching name. - Treating an
<ng-template>let-parameter as an@letdeclaration. - Forgetting that a local variable can shadow a component member.
Official Angular references
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