Add object id conversion function

js/object_id.js

@@ -0,0 +1,26 @@
+object_id_into_uint8array = function(id, arr) {
+    // passed array is exactly 16 bytes -- 12 for id, 3 blank, 1 for string pad length
+    // initialize all of them so that we can assume they're initialized on the rust side
+    const padding = id.length;
+    let skip_bytes = 12 - Math.ceil(padding / 2);
+
+    for (let byte = 0; byte < skip_bytes; byte++) {
+        arr[byte] = 0;
+    }
+
+    const offset = padding % 2;
+    // if there's an odd number of characters, grab one for the next byte
+    if (offset === 1) {
+        arr[skip_bytes] = parseInt(id.substr(0, 1), 16)
+        skip_bytes++;
+    }
+
+    for (let byte = 0; byte < 12 - skip_bytes; byte++) {
+        arr[byte + skip_bytes] = parseInt(id.substr(byte * 2 + offset, 2), 16)
+    }
+
+    arr[12] = 0;
+    arr[13] = 0;
+    arr[14] = 0;
+    arr[15] = padding;
+}