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---
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title: Basic markup
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---
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## Tags
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A lowercase tag, like `<div>`, denotes a regular HTML element. A capitalised tag, such as `<Widget>` or `<Namespace.Widget>`, indicates a _component_.
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```svelte
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<script>
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import Widget from './Widget.svelte';
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</script>
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<div>
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<Widget />
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</div>
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```
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## Attributes and props
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By default, attributes work exactly like their HTML counterparts.
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```svelte
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<div class="foo">
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<button disabled>can't touch this</button>
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</div>
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```
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As in HTML, values may be unquoted.
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<!-- prettier-ignore -->
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```svelte
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<input type=checkbox />
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```
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Attribute values can contain JavaScript expressions.
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```svelte
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<a href="page/{p}">page {p}</a>
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```
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Or they can _be_ JavaScript expressions.
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```svelte
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<button disabled={!clickable}>...</button>
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```
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Boolean attributes are included on the element if their value is [truthy](https://developer.mozilla.org/en-US/docs/Glossary/Truthy) and excluded if it's [falsy](https://developer.mozilla.org/en-US/docs/Glossary/Falsy).
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All other attributes are included unless their value is [nullish](https://developer.mozilla.org/en-US/docs/Glossary/Nullish) (`null` or `undefined`).
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```svelte
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<input required={false} placeholder="This input field is not required" />
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<div title={null}>This div has no title attribute</div>
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```
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An expression might include characters that would cause syntax highlighting to fail in regular HTML, so quoting the value is permitted. The quotes do not affect how the value is parsed:
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```svelte
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<button disabled={number !== 42}>...</button>
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```
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When the attribute name and value match (`name={name}`), they can be replaced with `{name}`.
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```svelte
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<button {disabled}>...</button>
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<!-- equivalent to
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<button disabled={disabled}>...</button>
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-->
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```
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By convention, values passed to components are referred to as _properties_ or _props_ rather than _attributes_, which are a feature of the DOM.
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As with elements, `name={name}` can be replaced with the `{name}` shorthand.
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```svelte
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<Widget foo={bar} answer={42} text="hello" />
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```
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_Spread attributes_ allow many attributes or properties to be passed to an element or component at once.
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An element or component can have multiple spread attributes, interspersed with regular ones.
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```svelte
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<Widget {...things} />
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```
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`$$props` references all props that are passed to a component, including ones that are not declared with `export`. It is not generally recommended, as it is difficult for Svelte to optimise. But it can be useful in rare cases – for example, when you don't know at compile time what props might be passed to a component.
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```svelte
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<Widget {...$$props} />
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```
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`$$restProps` contains only the props which are _not_ declared with `export`. It can be used to pass down other unknown attributes to an element in a component. It shares the same optimisation problems as `$$props`, and is likewise not recommended.
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```svelte
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<input {...$$restProps} />
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```
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> The `value` attribute of an `input` element or its children `option` elements must not be set with spread attributes when using `bind:group` or `bind:checked`. Svelte needs to be able to see the element's `value` directly in the markup in these cases so that it can link it to the bound variable.
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> Sometimes, the attribute order matters as Svelte sets attributes sequentially in JavaScript. For example, `<input type="range" min="0" max="1" value={0.5} step="0.1"/>`, Svelte will attempt to set the value to `1` (rounding up from 0.5 as the step by default is 1), and then set the step to `0.1`. To fix this, change it to `<input type="range" min="0" max="1" step="0.1" value={0.5}/>`.
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> Another example is `<img src="..." loading="lazy" />`. Svelte will set the img `src` before making the img element `loading="lazy"`, which is probably too late. Change this to `<img loading="lazy" src="...">` to make the image lazily loaded.
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## Text expressions
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```svelte
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{expression}
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```
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Text can also contain JavaScript expressions:
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> If you're using a regular expression (`RegExp`) [literal notation](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp#literal_notation_and_constructor), you'll need to wrap it in parentheses.
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```svelte
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<h1>Hello {name}!</h1>
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<p>{a} + {b} = {a + b}.</p>
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<div>{/^[A-Za-z ]+$/.test(value) ? x : y}</div>
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```
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## Comments
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You can use HTML comments inside components.
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```svelte
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<!-- this is a comment! --><h1>Hello world</h1>
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```
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Comments beginning with `svelte-ignore` disable warnings for the next block of markup. Usually, these are accessibility warnings; make sure that you're disabling them for a good reason.
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```svelte
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<!-- svelte-ignore a11y-autofocus -->
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<input bind:value={name} autofocus />
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```
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