implemented MergeSort

src/MergeSort.js

+async function MergeSort(EingangsArray, startIdx, endIdx, arrayCopy, updateBars, setColor, sortSpeed) {
+    if (startIdx >= endIdx) return;
+
+    // Split array
+    const cuttingEdge = Math.floor((startIdx + endIdx) / 2);
+
+    // Recursively sort both halves
+    await MergeSort(EingangsArray, startIdx, cuttingEdge, arrayCopy, updateBars, setColor, sortSpeed);
+    await MergeSort(EingangsArray, cuttingEdge + 1, endIdx, arrayCopy, updateBars, setColor, sortSpeed);
+
+    // Merge halves back togeteher
+    await merge(EingangsArray, startIdx, cuttingEdge, endIdx, arrayCopy, updateBars, setColor, sortSpeed);
+}
+
+async function merge(EingangsArray, startIdx, middleIdx, endIdx, arrayCopy, updateBars, setColor, sortSpeed) {
+    let i = startIdx;
+    let j = middleIdx + 1;
+    let k = startIdx;
+    const bars = document.querySelectorAll('.bar'); // get all bars
+    const sortSpeedSwitch = Number(sortSpeed);
+
+
+    // index exist?
+    const isValidIndex = (index) => index >= 0 && index < bars.length;
+
+    // Merge halves back togeteher
+    while (i <= middleIdx && j <= endIdx) {
+        if (isValidIndex(i) && isValidIndex(j)) {
+            // Change color of compared bars
+            bars[i].style.backgroundColor = 'red';
+            bars[j].style.backgroundColor = 'red';
+        }
+
+        switch (sortSpeedSwitch) {
+            case 0:
+                break; // No delay
+            case 40:
+                await new Promise(resolve => setTimeout(resolve, 90));
+                break;
+            case 100:
+                await new Promise(resolve => setTimeout(resolve, 200));
+                break;
+        }
+        if (EingangsArray[i] <= EingangsArray[j]) {
+            arrayCopy[k] = EingangsArray[i];
+            i++;
+        } else {
+            arrayCopy[k] = EingangsArray[j];
+            j++;
+        }
+
+        // Update Array
+        await updateArrayState(EingangsArray, arrayCopy, startIdx, endIdx, updateBars, sortSpeed);
+        if (isValidIndex(i - 1)) bars[i - 1].style.backgroundColor = ''; // default colr
+        if (isValidIndex(j - 1)) bars[j - 1].style.backgroundColor = '';
+
+        k++;
+    }
+
+    // Copy  from the LEFT half
+    while (i <= middleIdx) {
+        switch (sortSpeedSwitch) {
+            case 0:
+                break; // No delay
+            case 40:
+                await new Promise(resolve => setTimeout(resolve, 90));
+                break;
+            case 100:
+                await new Promise(resolve => setTimeout(resolve, 200));
+                break;
+        }
+
+        arrayCopy[k] = EingangsArray[i];
+        await updateArrayState(EingangsArray, arrayCopy, startIdx, endIdx, updateBars, sortSpeed);
+        if (isValidIndex(i)) bars[i].style.backgroundColor = '';
+
+        i++;
+        k++;
+    }
+
+    // Copy  from the RIGHT half
+    while (j <= endIdx) {
+        switch (sortSpeedSwitch) {
+            case 0:
+                break; // No delay
+            case 40:
+                await new Promise(resolve => setTimeout(resolve, 90));
+                break;
+            case 100:
+                await new Promise(resolve => setTimeout(resolve, 200));
+                break;
+        }
+
+        arrayCopy[k] = EingangsArray[j];
+        await updateArrayState(EingangsArray, arrayCopy, startIdx, endIdx, updateBars, sortSpeed);
+        if (isValidIndex(j)) bars[j].style.backgroundColor = '';
+
+        j++;
+        k++;
+    }
+
+    // Copy merged values back
+    for (let i = startIdx; i <= endIdx; i++) {
+        EingangsArray[i] = arrayCopy[i];
+    }
+
+    // adding to class 'finished'
+    if (endIdx - startIdx + 1 === EingangsArray.length) {
+        setColor(0);
+    }
+}
+
+async function updateArrayState(EingangsArray, arrayCopy, startIdx, endIdx, updateBars, sortSpeed) {
+    updateBars([...arrayCopy]);
+    await new Promise(resolve => setTimeout(resolve, sortSpeed));
+}
+
+export default async function startMergeSort(EingangsArray, updateBars, setFinish, sortSpeed) {
+    const arrayCopy = [...EingangsArray];
+
+    await MergeSort(EingangsArray, 0, EingangsArray.length - 1, arrayCopy, updateBars, setFinish, sortSpeed);
+}