Select bindings in Svelte - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to bind the select value to the variable.

Svelte

<script>
  let color = 'red';
</script>

<select [1]={color}>
  <option value="red">Red</option>
  <option value="green">Green</option>
  <option value="blue">Blue</option>
</select>

Drag options to blanks, or click blank then click option'

Abind:select

Bbind:value

Cbind:option

Dbind:choice

Attempts:

3 left

💡 Hint

Common Mistakes

Using bind:select instead of bind:value

Trying to bind to bind:option or bind:choice which do not exist

In Svelte, to bind the selected value of a <select> element to a variable, use bind:value.

2fill in blank

medium

Complete the code to bind the selected option in a multiple select.

Svelte

<script>
  let selectedColors = [];
</script>

<select multiple [1]={selectedColors}>
  <option value="red">Red</option>
  <option value="green">Green</option>
  <option value="blue">Blue</option>
</select>

Drag options to blanks, or click blank then click option'

Abind:items

Bbind:selected

Cbind:value

Dbind:options

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to use bind:selected or bind:options which are not valid

Not using bind:value for multiple select

For multiple select elements, bind:value binds to an array of selected values.

3fill in blank

hard

Fix the error in the code to correctly bind the select value.

Svelte

<script>
  let fruit = 'apple';
</script>

<select [1]={fruit}>
  <option value="apple">Apple</option>
  <option value="banana">Banana</option>
  <option value="orange">Orange</option>
</select>

Drag options to blanks, or click blank then click option'

Abind:fruit

Bbind:choice

Cbind:selection

Dbind:value

Attempts:

3 left

💡 Hint

Common Mistakes

Using bind:fruit which is not a valid binding

Trying to bind to bind:selection or bind:choice

The correct binding for the selected value is bind:value. Other bindings like bind:fruit do not work.

4fill in blank

hard

Fill both blanks to bind the select value and handle change event.

Svelte

<script>
  let city = 'Paris';
  function handleChange(event) {
    city = event.target.[1];
  }
</script>

<select [2]={city} on:change={handleChange}>
  <option value="Paris">Paris</option>
  <option value="London">London</option>
  <option value="Tokyo">Tokyo</option>
</select>

Drag options to blanks, or click blank then click option'

Avalue

Bselected

Cbind:value

Dbind:selected

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'selected' instead of 'value' in event target

Using 'bind:selected' instead of 'bind:value'

The event target's value property holds the selected option's value. The select element binds with bind:value.

5fill in blank

hard

Fill all three blanks to bind a select with options from an array and show the selected value.

Svelte

<script>
  let fruits = ['Apple', 'Banana', 'Cherry'];
  let selectedFruit = fruits[0];
</script>

<select [1]={selectedFruit}>
  {#each fruits as BLANK_2}
    <option value=[2]>[2]</option>
  {/each}
</select>

<p>You selected: {selectedFruit}</p>

Drag options to blanks, or click blank then click option'

Abind:value

Bfruit

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names inside the each block

Not binding the select value properly

Use bind:value to bind the select value. The {#each} block iterates over fruits with variable fruit. The option's value and text use fruit.

Practice

1. What does the bind:value directive do in a Svelte <select> element?

easy

A. It disables the select dropdown.

B. It styles the selected option with a special color.

C. It links the selected option to a variable, updating it automatically.

D. It creates a new option dynamically.

Solution

1. Step 1: Understand bind:value usage

   The bind:value directive connects the selected option's value to a variable in Svelte, so changes update the variable automatically.

2. Step 2: Analyze other options

   Options A, B, and D describe unrelated behaviors: disabling, styling, or creating options, which bind:value does not do.

3. Final Answer:

   It links the selected option to a variable, updating it automatically. -> Option C

4. Quick Check:

   Select binding = automatic variable update [OK]

Hint: Remember: bind:value syncs select with variable [OK]

Common Mistakes:

• Thinking bind:value styles the select
• Confusing bind:value with disabling the select
• Assuming bind:value adds options

2. Which of the following is the correct syntax to bind a variable named color to a <select> element in Svelte?

easy

A. <select bind:value={color}>

B. <select bind:color>

C. <select value={color}>

D. <select bind:select={color}>

Solution

1. Step 1: Recall Svelte binding syntax

   In Svelte, to bind a variable to the value of a select, use bind:value={variable}.

2. Step 2: Check each option

   <select bind:value={color}> matches correct syntax. <select bind:color> uses incorrect binding name. <select value={color}> only sets value but does not bind. <select bind:select={color}> uses invalid binding name.

3. Final Answer:

   <select bind:value={color}> -> Option A

4. Quick Check:

   Correct bind syntax = bind:value={variable} [OK]

Hint: Use bind:value={variable} for select binding [OK]

Common Mistakes:

• Using bind:color instead of bind:value
• Setting value without bind
• Using incorrect binding names

3. Given this Svelte code:

  <script>
    let fruit = 'apple';
  </script>

  <select bind:value={fruit}>
    <option value='apple'>Apple</option>
    <option value='banana'>Banana</option>
    <option value='cherry'>Cherry</option>
  </select>

  <p>Selected fruit: {fruit}</p>

What will be displayed initially in the paragraph?

medium

A. Selected fruit: (empty)

B. Selected fruit: banana

C. Selected fruit: cherry

D. Selected fruit: apple

Solution

1. Step 1: Check initial variable value

   The variable fruit is initialized to 'apple'.

2. Step 2: Understand binding effect

   The select binds its value to fruit, so the option with value 'apple' is selected initially, and the paragraph shows that value.

3. Final Answer:

   Selected fruit: apple -> Option D

4. Quick Check:

   Initial variable value = displayed text [OK]

Hint: Initial variable sets selected option and displayed text [OK]

Common Mistakes:

• Assuming default select is empty
• Confusing option order with initial value
• Ignoring variable initialization

4. Identify the error in this Svelte code snippet:

<script>
  let choice;
</script>

<select bind:value=choice>
  <option value='1'>One</option>
  <option value='2'>Two</option>
</select>

medium

A. Missing curly braces around variable in bind:value

B. Options must have numeric values only

C. Variable choice must be initialized to a string

D. bind:value cannot be used on select

Solution

1. Step 1: Check bind:value syntax

   In Svelte, binding requires curly braces around the variable: bind:value={choice}.

2. Step 2: Verify other options

   Options A, B, and C are incorrect because bind:value is valid on select, options can have string values, and variables can be undefined initially.

3. Final Answer:

   Missing curly braces around variable in bind:value -> Option A

4. Quick Check:

   bind:value requires {variable} syntax [OK]

Hint: Always use curly braces in bind:value={variable} [OK]

Common Mistakes:

• Omitting curly braces in bind:value
• Thinking variables must be initialized
• Believing bind:value is invalid on select

5. You want to create a <select> in Svelte that allows users to pick a fruit, but if the user selects "None", the bound variable should be set to null instead of the string "none". Which approach correctly achieves this?

hard

A. Use <select bind:value={fruit}> with an <option value={null}>None</option>

B. Use <select bind:value={fruit}> and in a reactive statement set fruit = null if fruit === 'none'

C. Use <select bind:value={fruit}> and set the option value to undefined for None

D. Use <select bind:value={fruit}> and convert fruit to null on form submit only

Solution

1. Step 1: Understand option values and binding

   HTML option values are strings, so setting value={null} becomes "null" string, not JavaScript null.

2. Step 2: Use reactive statement to convert value

   Use <select bind:value={fruit}> and in a reactive statement set fruit = null if fruit === 'none' uses a reactive statement to watch fruit and set it to null when the string 'none' is selected, correctly converting the value.

3. Step 3: Analyze other options

   Use <select bind:value={fruit}> with an <option value={null}>None</option> incorrectly tries to bind null directly as value. Use <select bind:value={fruit}> and set the option value to undefined for None uses undefined which becomes string. Use <select bind:value={fruit}> and convert fruit to null on form submit only delays conversion, not reactive.

4. Final Answer:

   Use <select bind:value={fruit}> and in a reactive statement set fruit = null if fruit === 'none' -> Option B

5. Quick Check:

   Reactive conversion handles string to null correctly [OK]

Hint: Use reactive code to convert string 'none' to null [OK]

Common Mistakes:

• Trying to bind null directly as option value
• Assuming option values can be non-string
• Delaying conversion until form submit