diff --git a/js_body_filter.t b/js_body_filter.t
new file mode 100644
index 0000000..b90a250
--- /dev/null
+++ b/js_body_filter.t
@@ -0,0 +1,168 @@
+#!/usr/bin/perl
+
+# (C) Dmitry Volyntsev
+# (C) Nginx, Inc.
+
+# Tests for http njs module, body filter.
+
+###############################################################################
+
+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 $t = Test::Nginx->new()->has(qw/http proxy/)
+	->write_file_expand('nginx.conf', <<'EOF');
+
+%%TEST_GLOBALS%%
+
+daemon off;
+
+events {
+}
+
+http {
+    %%TEST_GLOBALS_HTTP%%
+
+    js_import test.js;
+
+    server {
+        listen       127.0.0.1:8080;
+        server_name  localhost;
+
+        location /njs {
+            js_content test.njs;
+        }
+
+        location /append {
+            js_body_filter test.append;
+            proxy_pass http://127.0.0.1:8081/source;
+        }
+
+        location /buffer_type {
+            js_body_filter test.buffer_type buffer_type=buffer;
+            proxy_pass http://127.0.0.1:8081/source;
+        }
+
+        location /forward {
+            js_body_filter test.forward buffer_type=string;
+            proxy_pass http://127.0.0.1:8081/source;
+        }
+
+        location /filter {
+            proxy_buffering off;
+            js_body_filter test.filter;
+            proxy_pass http://127.0.0.1:8081/source;
+        }
+
+        location /prepend {
+            js_body_filter test.prepend;
+            proxy_pass http://127.0.0.1:8081/source;
+        }
+    }
+
+    server {
+        listen       127.0.0.1:8081;
+        server_name  localhost;
+
+        location /source {
+            postpone_output 1;
+            js_content test.source;
+        }
+    }
+}
+
+EOF
+
+$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);
+        }
+    }
+
+    var collect = Buffer.from([]);
+    function buffer_type(r, data, flags) {
+        collect = Buffer.concat([collect, data]);
+
+        if (flags.last) {
+            r.sendBuffer(collect, 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 filter(r, data, flags) {
+        if (flags.last || data.length >= Number(r.args.len)) {
+            r.sendBuffer(`\${data}|`, flags);
+
+            if (r.args.dup && !flags.last) {
+                r.sendBuffer(data, flags);
+            }
+        }
+    }
+
+    function forward(r, data, flags) {
+        r.sendBuffer(data, flags);
+    }
+
+    function prepend(r, data, flags) {
+        r.sendBuffer("XXX");
+        r.sendBuffer(data, flags);
+        r.done();
+    }
+
+    export default {njs: test_njs, append, buffer_type, filter, forward,
+                    prepend, source};
+
+EOF
+
+$t->try_run('no njs body filter')->plan(6);
+
+###############################################################################
+
+like(http_get('/append'), qr/AAABBCDDDDXXX/, 'append');
+like(http_get('/buffer_type'), qr/AAABBCDDDD/, 'buffer type');
+like(http_get('/forward'), qr/AAABBCDDDD/, 'forward');
+like(http_get('/filter?len=3'), qr/AAA|DDDD|/, 'filter 3');
+like(http_get('/filter?len=2&dup=1'), qr/AAA|AAABB|BBDDDD|DDDD/,
+	'filter 2 dup');
+like(http_get('/prepend'), qr/XXXAAABBCDDDD/, 'prepend');
+
+###############################################################################