Angular中模板引用变量的scope是什么？

Question

What is the scope of the template reference variable in Angular?

I can not find a clear answer to my question in documentation. Even though empirically I can say that the whole template can access the template reference variable.

1 Is it the case? Is the template reference variable guaranteed to be accessible in the whole template?

2 Or is the template reference variable accessible only in the child and sibling elements of the element which is referenced by the template reference variable?

Over here I found the following statement:

Use template variables to refer to elements — The newHero template variable refers to the <input> element. You can reference newHero from any sibling or child of the <input> element.

Does it mean that only the 2 is guaranteed by Angular?

Answer 1

Template reference variable could be accessed from anywhere in the template as long as the corresponding element is present in the DOM .

For eg. you cannot access a template ref variable inside an <ng-template> element if it is not yet rendered.

<ng-template #templateOne let-message let-showAdditional="show">
  <div #templateDiv>
    One <br />
  </div>
</ng-template>

<ng-container *ngIf="templateDiv">
  Got template div
</ng-container>

Here Angular will throw an error

Property 'templateDiv' does not exist on type 'SomeComponent'.

because the element that is referenced by the variable is not present in the DOM.

---

Regarding your point 2.

You can reference newHero from any sibling or child of the element.

They were referring to the specific tutorial. Notice it didn't say

You can reference newHero only from any sibling or child of the element.

Answer 2

As stated here :

You can refer to a template reference variable anywhere in the component's template.