new file mode 100644
--- /dev/null
+++ b/js_body_filter_if.t
@@ -0,0 +1,127 @@
+#!/usr/bin/perl
+
+# (C) Dmitry Volyntsev
+# (C) Nginx, Inc.
+
+# Tests for http njs module, body filter, if context.
+
+###############################################################################
+
+use warnings;
+use strict;
+
+use Test::More;
+
+BEGIN { use FindBin; chdir($FindBin::Bin); }
+
+use lib 'lib';
+use Test::Nginx;
+
+###############################################################################
+
+select STDERR; $| = 1;
+select STDOUT; $| = 1;
+
+my $t = Test::Nginx->new()->has(qw/http proxy rewrite/)
+	->write_file_expand('nginx.conf', <<'EOF');
+
+%%TEST_GLOBALS%%
+
+daemon off;
+
+events {
+}
+
+http {
+    %%TEST_GLOBALS_HTTP%%
+
+    js_import test.js;
+
+    server {
+        listen       127.0.0.1:8080;
+        server_name  localhost;
+
+        location /njs {
+            js_content test.njs;
+        }
+
+        location /filter {
+            if ($arg_name ~ "prepend") {
+                js_body_filter test.prepend;
+            }
+
+            if ($arg_name ~ "append") {
+                js_body_filter test.append;
+            }
+
+            js_body_filter test.should_not_be_called;
+
+            proxy_pass http://127.0.0.1:8081/source;
+        }
+    }
+
+    server {
+        listen       127.0.0.1:8081;
+        server_name  localhost;
+
+        location /source {
+            postpone_output 1;
+            js_content test.source;
+        }
+    }
+}
+
+EOF
+
+$t->write_file('test.js', <<EOF);
+    function test_njs(r) {
+        r.return(200, njs.version);
+    }
+
+    function append(r, data, flags) {
+        r.sendBuffer(data, {last:false});
+
+        if (flags.last) {
+            r.sendBuffer("XXX", flags);
+        }
+    }
+
+    function chain(chunks, i) {
+        if (i < chunks.length) {
+            chunks.r.send(chunks[i++]);
+            setTimeout(chunks.chain, chunks.delay, chunks, i);
+
+        } else {
+            chunks.r.finish();
+        }
+    }
+
+    function source(r) {
+        var chunks = ['AAA', 'BB', 'C', 'DDDD'];
+        chunks.delay = 5;
+        chunks.r = r;
+        chunks.chain = chain;
+
+        r.status = 200;
+        r.sendHeader();
+        chain(chunks, 0);
+    }
+
+    function prepend(r, data, flags) {
+        r.sendBuffer("XXX");
+        r.sendBuffer(data, flags);
+        r.done();
+    }
+
+    export default {njs: test_njs, append, prepend, source};
+
+EOF
+
+$t->try_run('no njs body filter')->plan(2);
+
+###############################################################################
+
+like(http_get('/filter?name=append'), qr/AAABBCDDDDXXX/, 'append');
+like(http_get('/filter?name=prepend'), qr/XXXAAABBCDDDD/, 'prepend');
+
+###############################################################################