1 files changed, 34 insertions, 0 deletions
diff --git a/web/utils.js b/web/utils.js
new file mode 100644
index 0000000..d7cf657
--- /dev/null
+++ b/web/utils.js
@@ -0,0 +1,34 @@
+// format as hex number
+export const hex = (n) => '0x' + n.toString(16);
+
+// concatenate Uint8Array
+export const concat = (a, b) => {
+  const arr = new Uint8Array(a.length + b.length);
+  arr.set(a);
+  arr.set(b, a.length);
+  return arr;
+};
+
+// like Array.reduce() but await each iteration
+export const areduce = async (array, fn, state=null) => {
+  for (const val of array) {
+    state = await fn(val, state);
+  }
+  return state;
+};
+
+// generate array with range [a, b[ or [0, a[
+export const range = (a, b=null) => {
+  if (b === null) {
+    b = a;
+    a = 0;
+  }
+
+  const res = [];
+  for (let i = a; i < b; i++)
+    res.push(i);
+  return res;
+};
+
+// return a Promise that resolves in n seconds
+export const sleep = (n) => new Promise(res => setTimeout(res, n*1000));