1 files changed, 28 insertions, 0 deletions
diff --git a/src/crypto/rand/rand_js.go b/src/crypto/rand/rand_js.go
new file mode 100644
index 0000000..91e69fa
--- /dev/null
+++ b/src/crypto/rand/rand_js.go
@@ -0,0 +1,28 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build js && wasm
+
+package rand
+
+import "syscall/js"
+
+func init() {
+	Reader = &reader{}
+}
+
+var jsCrypto = js.Global().Get("crypto")
+var uint8Array = js.Global().Get("Uint8Array")
+
+// reader implements a pseudorandom generator
+// using JavaScript crypto.getRandomValues method.
+// See https://developer.mozilla.org/en-US/docs/Web/API/Crypto/getRandomValues.
+type reader struct{}
+
+func (r *reader) Read(b []byte) (int, error) {
+	a := uint8Array.New(len(b))
+	jsCrypto.Call("getRandomValues", a)
+	js.CopyBytesToGo(b, a)
+	return len(b), nil
+}