Template reference for direct access in Angular - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a template reference variable in Angular?

A template reference variable is a way to access a DOM element or Angular component directly within the template using a special syntax with the # symbol.

beginner

How do you declare a template reference variable for an input element?

You declare it by adding #variableName inside the input tag, for example: <input #myInput>. This lets you access the input element directly in the template.

intermediate

How can you use a template reference variable to get the value of an input field in Angular?

You can use the variable inside the template, for example: <button (click)="doSomething(myInput.value)">. This passes the current value of the input to the component method.

intermediate

Can template reference variables access Angular components as well as DOM elements?

Yes, if you assign a template reference variable to a component selector, you can access the component instance and call its methods or access its properties directly in the template.

beginner

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

The scope of a template reference variable is limited to the template where it is declared. It cannot be accessed in other templates or component classes directly.

How do you declare a template reference variable named 'inputBox' on an input element?

A <input #inputBox>

B <input ref='inputBox'>

C <input var='inputBox'>

D <input $inputBox>

Template reference variables are declared using the # symbol followed by the variable name inside the element tag.

What can a template reference variable NOT directly access?

A Component class properties

B Angular components

C DOM elements

D Template elements

Template reference variables cannot directly access component class properties; they access elements or component instances in the template.

Which of these is a valid use of a template reference variable in a button click event?

A <button (click)="submit(#inputRef.value)">

B <button (click)="submit(inputRef.value)">

C <button (click)="submit($inputRef.value)">

D <button (click)="submit(ref.inputRef.value)">

You use the variable name directly without # inside event bindings.

If you declare , what does compRef represent?

A The DOM element of my-comp

B A CSS class applied to my-comp

C A string with the component name

D The Angular component instance of my-comp

When used on a component selector, the template reference variable points to the component instance.

Where can you use a template reference variable declared in a template?

A Inside the component class

B Anywhere in the Angular app

C Only inside the same template

D In sibling components

Template reference variables are only accessible within the template where they are declared.

Explain how to create and use a template reference variable to get the value of an input field in Angular.

Think about how you can grab the input's current text without using component code.

Describe the difference between accessing a DOM element and an Angular component using template reference variables.

Consider what you get when you put #var on a normal HTML tag vs a component tag.

Practice

1. What is the main purpose of a #templateReference in Angular templates?

easy

A. To bind data between components

B. To define a new Angular component

C. To create a service for dependency injection

D. To directly access a DOM element or component instance in the template

Solution

1. Step 1: Understand what template references do

   Template references let you name elements or components in the template for direct access.

2. Step 2: Identify their use

   They are used to access DOM elements or component instances directly without extra code.

3. Final Answer:

   To directly access a DOM element or component instance in the template -> Option D

4. Quick Check:

   Template reference = direct element/component access [OK]

Hint: Template references name elements for direct access [OK]

Common Mistakes:

• Confusing template references with component declarations
• Thinking they create services
• Assuming they handle data binding

2. Which of the following is the correct syntax to create a template reference named inputBox on an <input> element?

easy

A.

B.

C.

D.

Solution

1. Step 1: Recall Angular template reference syntax

   Angular uses the hash symbol (#) to declare template references.

2. Step 2: Check each option

   Only #inputBox is valid syntax for template references on elements.

3. Final Answer:

   <input #inputBox> -> Option B

4. Quick Check:

   Use # for template references [OK]

Hint: Use # before name to create template reference [OK]

Common Mistakes:

• Using ref= instead of #
• Using * which is for structural directives
• Using $ which is invalid here

3. Given this template snippet:

<input #myInput type="text">
<button (click)="myInput.focus()">Focus</button>

What happens when the button is clicked?

medium

A. Nothing happens because focus() is not a valid method

B. An error occurs because myInput is undefined

C. The input box receives keyboard focus

D. The button text changes to 'Focus'

Solution

1. Step 1: Understand the template reference usage

   The #myInput references the input element, allowing direct access to its DOM methods.

2. Step 2: Analyze the click event

   Click calls myInput.focus(), which sets keyboard focus on the input element.

3. Final Answer:

   The input box receives keyboard focus -> Option C

4. Quick Check:

   Template ref calls focus() = input focused [OK]

Hint: Template refs access DOM methods like focus() [OK]

Common Mistakes:

• Assuming template refs are undefined in event handlers
• Thinking focus() is invalid on input elements
• Expecting button text to change

4. Consider this Angular template:

<input #userInput type="text">
<button (click)="logValue()">Log</button>

And this component code:

logValue() {
  console.log(userInput.value);
}

What is the problem here?

medium

A. The userInput template reference is not accessible in the component class

B. The logValue method is missing a parameter

C. The console.log statement is incorrect syntax

D. The button click event should be (click)="logValue(userInput)"

Solution

1. Step 1: Understand template reference scope

   Template references exist only in the template, not in the component class directly.

2. Step 2: Identify why userInput is undefined in the class

   Trying to access userInput in the class without passing it causes an error.

3. Final Answer:

   The userInput template reference is not accessible in the component class -> Option A

4. Quick Check:

   Template refs not in class scope [OK]

Hint: Template refs only exist in template, not class [OK]

Common Mistakes:

• Assuming template refs are class properties
• Forgetting to pass template ref as method argument
• Confusing template refs with ViewChild

5. You want to create a form with an input and a button that clears the input when clicked. Using a template reference #inputRef, which template code correctly implements this behavior?

hard

A.
Clear

B.
Clear

C.
Clear

D.
Clear

Solution

1. Step 1: Understand how to clear input value via template reference

   Directly setting inputRef.value = '' clears the input content.

2. Step 2: Check other options for correctness

   Options B, C, and D call undefined or non-existent methods: clear() is undefined in the component, and clear() and reset() are not methods on input elements.

3. Final Answer:

   <input #inputRef type="text"> <button (click)="inputRef.value = ''">Clear</button> -> Option A

4. Quick Check:

   Set inputRef.value to empty string to clear [OK]

Hint: Set inputRef.value = '' to clear input [OK]

Common Mistakes:

• Calling non-existent methods like clear() or reset() on input
• Trying to call component methods without passing template ref
• Confusing template ref usage with reactive forms