Remove from* variants, move fromString to stringTo (#233)

* Remove from* variants, move fromString to stringTo

* Bump

packages/util/src/string/toU8a.ts

@@ -0,0 +1,26 @@
+// Copyright 2017-2018 @polkadot/util authors & contributors
+// This software may be modified and distributed under the terms
+// of the ISC license. See the LICENSE file for details.
+
+import './polyfill/textEncoder';
+
+const encoder = new TextEncoder();
+
+/**
+ * @name stringToU8a
+ * @signature stringToU8a (value?: string): UInt8Array
+ * @summary Creates a Uint8Array object from a utf-8 string.
+ * @description
+ * String input values return the actual encoded `UInt8Array`. `null` or `undefined` values returns an empty encoded array.
+ * @example
+ *   import { stringToU8a } from '@polkadot/util';
+ *
+ *   stringToU8a('hello'); // [0x68, 0x65, 0x6c, 0x6c, 0x6f]
+ */
+export default function stringToU8a (value?: string): Uint8Array {
+  if (!value) {
+    return new Uint8Array([]);
+  }
+
+  return encoder.encode(value);
+}