Added snippet for getDifferenceInSeconds

snippets/covertArrayTo2DMatrix.md

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+---
+title: covertArrayTo2DMatrix
+tags: array,intermediate
+---
+
+Returns array of arrays, with internal arrays of size (columns) supplied.
+
+```js
+const covertArrayTo2DMatrix = (items, columns) => {
+  let data = []
+  if (items?.length && columns) {
+    const rows = columns ? Math.ceil((items?.length ?? 0) / columns) : 0
+    for (let i = 0; i < rows; i++) {
+      let row = []
+      for (let j = 0; j < columns; j++) {
+        const element = items[i + j + i * (columns - 1)]
+        if (element) {
+          row.push(element)
+        }
+      }
+
+      data.push(row)
+    }
+  }
+  return data
+}
+```
+
+```js
+covertArrayTo2DMatrix([1, 2, 3, 4, 5, 6], 3); // [[1, 2, 3], [4, 5, 6]]
+covertArrayTo2DMatrix([1, 2, 3, 4, 5, 6], 2); // [[1, 2], [3, 4], [5, 6]]
+covertArrayTo2DMatrix([1, 2, 3, 4, 5], 3); // [[1, 2, 3], [4, 5]]
+```

snippets/getDifferenceInSeconds.md

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+---
+title: getDifferenceInSeconds
+tags: dates,beginner
+---
+
+Returns the diffrence in seconds between 2 supplied dates.
+
+```js
+const getDifferenceInSeconds = (start, end) =>
+  (end.getTime() - start.getTime()) / 1000;
+```
+
+```js
+getDifferenceInSeconds(new Date('2020-12-24 00:00:15'), new Date('2020-12-24 00:00:17')); // 2
+```