Default prop values in Svelte - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a default prop value in Svelte?

A default prop value is a value assigned to a component's prop that is used when no value is passed from the parent component.

beginner

How do you set a default prop value in a Svelte component?

You assign a value to the prop variable when declaring it with <code>export let</code>. For example: <code>export let name = 'Guest';</code>

beginner

What happens if a parent component passes a value to a prop that has a default value in Svelte?

The passed value overrides the default value, so the component uses the parent's value instead of the default.

intermediate

Can default prop values in Svelte be any data type?

Yes, default prop values can be strings, numbers, booleans, objects, arrays, or any valid JavaScript value.

beginner

Why are default prop values useful in Svelte components?

They make components more flexible and easier to use by providing fallback values, so the parent doesn't have to pass every prop every time.

How do you declare a prop with a default value in Svelte?

A export let propName = defaultValue;

B let propName: defaultValue;

C propName = export default defaultValue;

D default propName = defaultValue;

In Svelte, you use export let propName = defaultValue; to declare a prop with a default value.

If a parent component passes a value to a prop, what happens to the default value?

A The default value is ignored and the passed value is used.

B The default value and passed value are merged.

C The default value overrides the passed value.

D An error occurs.

The passed value overrides the default value in Svelte props.

Which of these is a valid default prop value in Svelte?

A default let count = 0;

B export let count;

C export let count = 0;

D let count = 0;

Only export let count = 0; correctly declares a prop with a default value.

Can default prop values be objects in Svelte?

A Only strings are allowed.

B No, only primitive types are allowed.

C Only arrays are allowed, not objects.

D Yes, for example: export let settings = { theme: 'dark' };

Svelte allows any JavaScript value as a default prop, including objects.

Why might you use default prop values in your Svelte components?

A To make props read-only.

B To provide fallback values and simplify component usage.

C To prevent props from being passed.

D To automatically update props from the server.

Default prop values provide fallback values, making components easier to use.

Explain how to set and use default prop values in a Svelte component.

Think about how you declare props and assign values in Svelte.

Describe why default prop values improve component flexibility in Svelte.

Consider what happens if a parent forgets to pass a prop.