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Part 1 / Bindings / Group inputs

If you have multiple inputs relating to the same value, you can use bind:group along with the value attribute. Radio inputs in the same group are mutually exclusive; checkbox inputs in the same group form an array of selected values.

Add bind:group to each input:

<input type=radio bind:group={scoops} name="scoops" value={1}>

In this case, we could make the code simpler by moving the checkbox inputs into an each block. First, add a menu variable to the <script> block...

let menu = ['Cookies and cream', 'Mint choc chip', 'Raspberry ripple'];

...then replace the second section:

<h2>Flavours</h2>

{#each menu as flavour}
	<label>
		<input type=checkbox bind:group={flavours} name="flavours" value={flavour}>
		{flavour}
	</label>
{/each}

It's now easy to expand our ice cream menu in new and exciting directions.

Next: Textarea inputs

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<script>
	let scoops = 1;
	let flavours = ['Mint choc chip'];
 
	function join(flavours) {
		if (flavours.length === 1) return flavours[0];
		return `${flavours.slice(0, -1).join(', ')} and ${flavours[flavours.length - 1]}`;
	}
</script>
 
<h2>Size</h2>
 
<label>
	<input type=radio group={scoops} name="scoops" value={1}>
	One scoop
</label>
 
<label>
	<input type=radio group={scoops} name="scoops" value={2}>
	Two scoops
</label>
 
<label>
	<input type=radio group={scoops} name="scoops" value={3}>
	Three scoops
</label>
 
<h2>Flavours</h2>
 
<label>
	<input type=checkbox group={flavours} name="flavours" value="Cookies and cream">
	Cookies and cream
</label>
 
<label>
	<input type=checkbox group={flavours} name="flavours" value="Mint choc chip">
	Mint choc chip
</label>
 
<label>
	<input type=checkbox group={flavours} name="flavours" value="Raspberry ripple">
	Raspberry ripple
</label>
 
{#if flavours.length === 0}
	<p>Please select at least one flavour</p>
{:else if flavours.length > scoops}
	<p>Can't order more flavours than scoops!</p>
{:else}
	<p>
		You ordered {scoops} {scoops === 1 ? 'scoop' : 'scoops'}
		of {join(flavours)}
	</p>
{/if}
initialising