Rework conditions for Button

- Was prefetching mailto links, so needs to detect if url string is starting
- Check if it actually has slots, then add a class

src/components/atoms/Button.svelte

@@ -19,14 +19,14 @@
         className,
         effect ? effect : undefined,
         ...[color, size].map(variant => variant && `${className}--${variant}`),
-        $$slots ? `has-icon-${slotPosition}` : undefined,
+        Object.keys($$slots).length !== 0 ? `has-icon-${slotPosition}` : undefined,
         $$props.class
     ].join(' ').trim()
 
     // Define external links
-    let rel: string, target: string
-    $: isExternal = /(http(s?)):\/\//i.test(url)
-    $: rel = isExternal ? 'external noopener noreferrer' : null
+    $: isExternal = /^(http|https):\/\//i.test(url)
+    $: isProtocol = /^(mailto|tel):/i.test(url)
+    $: rel = isExternal ? 'external noopener' : null
     $: target = isExternal ? '_blank' : null
 </script>
 
@@ -43,9 +43,9 @@
 {:else if tag === 'a'}
     <a
         href={url} class={classes}
-        {rel} {target}
-        sveltekit:prefetch={url && isExternal ? null : true}
-        sveltekit:noscroll={isExternal ? null : true}
+        {target} {rel}
+        sveltekit:prefetch={url && (isExternal || isProtocol) ? null : true}
+        sveltekit:noscroll={isExternal || isProtocol ? null : true}
         {disabled}
         tabindex="0"
         on:click