add context menu

src/components/PopperMenu.svelte

@@ -0,0 +1,55 @@
+<span bind:this={btn} on:click={() => openMenu()}>
+    <slot name="btn">
+        <button>button</button>
+    </slot>
+</span>
+
+<div class="contextMenu__overlay" class:active={isActive} on:click={() => closeMenu()}></div>
+<div class="contextMenu" bind:this={content} class:active={isActive}>
+    <slot name="content">
+        No content
+    </slot>
+</div>
+
+<script>
+import { onMount } from 'svelte';
+import { createPopper } from '@popperjs/core';
+import detectOverflow from '@popperjs/core/lib/utils/detectOverflow.js';
+
+let btn
+let content
+let isActive = false
+
+function openMenu () {
+    isActive = true
+}
+
+function closeMenu () {
+    isActive = false
+}
+
+onMount(() => {
+    createPopper(btn, content, {
+    placement: 'left-start',
+    modifiers: [
+        {
+            name: 'offset',
+            options: {
+                offset: ({ reference, popper }) => {
+                    return [-10, -reference.width - 5];
+                }
+            }
+        },
+        {
+            name: 'myModifier',
+            enabled: true,
+            phase: 'main',
+            requiresIfExists: ['offset'],
+            fn({ state }) {
+                const overflow = detectOverflow(state);
+            }
+        }
+    ]
+    });
+});
+</script>