Basic njs support.

20 files changed, 507 insertions, 44 deletions

diff --git a/auto/help b/auto/help
index e2b81bc7..a3884679 100644
--- a/auto/help
+++ b/auto/help
@@ -41,6 +41,8 @@ cat << END
 
   --openssl            enable OpenSSL library usage
 
+  --njs                enable NJS library usage
+
   --debug              enable debug logging
 
 
diff --git a/auto/njs b/auto/njs
new file mode 100644
index 00000000..72304793
--- /dev/null
+++ b/auto/njs
@@ -0,0 +1,41 @@
+
+# Copyright (C) NGINX, Inc.
+
+
+nxt_found=no
+NXT_HAVE_NJS=NO
+
+NXT_NJS_CFLAGS=
+NXT_NJS_AUX_CFLAGS=
+NXT_NJS_LIBS="-lnjs"
+NXT_NJS_AUX_LIBS="$NXT_LIBM $NXT_LIB_AUX_LIBS"
+
+nxt_feature="NJS"
+nxt_feature_name=NXT_HAVE_NJS
+nxt_feature_run=no
+nxt_feature_incs="$NXT_NJS_CFLAGS $NXT_NJS_AUX_CFLAGS"
+nxt_feature_libs="$NXT_NJS_LIBS $NXT_NJS_AUX_LIBS"
+nxt_feature_test="#include <njs.h>
+
+                  int main(void) {
+                      njs_vm_t      *vm;
+                      njs_vm_opt_t  opts;
+
+                      njs_vm_opt_init(&opts);
+
+                      vm = njs_vm_create(&opts);
+                      if (vm == NULL)
+                          return 1;
+                      return 0;
+                  }"
+. auto/feature
+
+if [ $nxt_found = no ]; then
+    $echo
+    $echo $0: error: no NJS library found.
+    $echo
+    exit 1;
+fi
+
+NXT_LIB_AUX_CFLAGS="$NXT_LIB_AUX_CFLAGS $NXT_NJS_CFLAGS"
+NXT_LIB_AUX_LIBS="$NXT_NJS_LIBS $NXT_LIB_AUX_LIBS"
diff --git a/auto/options b/auto/options
index 572d8a9b..abcf531d 100644
--- a/auto/options
+++ b/auto/options
@@ -28,6 +28,8 @@ NXT_GNUTLS=NO
 NXT_CYASSL=NO
 NXT_POLARSSL=NO
 
+NXT_NJS=NO
+
 NXT_TEST_BUILD_EPOLL=NO
 NXT_TEST_BUILD_EVENTPORT=NO
 NXT_TEST_BUILD_DEVPOLL=NO
@@ -85,6 +87,8 @@ do
         --cyassl)                        NXT_CYASSL=YES                      ;;
         --polarssl)                      NXT_POLARSSL=YES                    ;;
 
+        --njs)                           NXT_NJS=YES                         ;;
+
         --test-build-epoll)              NXT_TEST_BUILD_EPOLL=YES            ;;
         --test-build-eventport)          NXT_TEST_BUILD_EVENTPORT=YES        ;;
         --test-build-devpoll)            NXT_TEST_BUILD_DEVPOLL=YES          ;;
diff --git a/auto/sources b/auto/sources
index 7d3f62cf..9f9a27f7 100644
--- a/auto/sources
+++ b/auto/sources
@@ -135,6 +135,10 @@ NXT_LIB_POLARSSL_SRCS="src/nxt_polarssl.c"
 NXT_LIB_PCRE_SRCS="src/nxt_pcre.c"
 NXT_LIB_PCRE2_SRCS="src/nxt_pcre2.c"
 
+if [ "$NXT_NJS" != "NO" ]; then
+    NXT_LIB_SRCS="$NXT_LIB_SRCS src/nxt_js.c"
+fi
+
 NXT_LIB_EPOLL_SRCS="src/nxt_epoll_engine.c"
 NXT_LIB_KQUEUE_SRCS="src/nxt_kqueue_engine.c"
 NXT_LIB_EVENTPORT_SRCS="src/nxt_eventport_engine.c"
diff --git a/auto/summary b/auto/summary
index 79e7ce34..c8a49d08 100644
--- a/auto/summary
+++ b/auto/summary
@@ -28,6 +28,7 @@ Unit configuration summary:
   Unix domain sockets support: $NXT_UNIX_DOMAIN
   TLS support: ............... $NXT_OPENSSL
   Regex support: ............. $NXT_REGEX
+  NJS support: ............... $NXT_NJS
 
   process isolation: ......... $NXT_ISOLATION
 
diff --git a/configure b/configure
index ea86e18e..c21973eb 100755
--- a/configure
+++ b/configure
@@ -171,5 +171,9 @@ NXT_LIB_AUX_LIBS="$NXT_OPENSSL_LIBS $NXT_GNUTLS_LIBS \\
                     $NXT_CYASSL_LIBS $NXT_POLARSSL_LIBS \\
                     $NXT_PCRE_LIB"
 
+if [ $NXT_NJS != NO ]; then
+    . auto/njs
+fi
+
 . auto/make
 . auto/summary
diff --git a/docs/changes.xml b/docs/changes.xml
index 014f243d..0c52c628 100644
--- a/docs/changes.xml
+++ b/docs/changes.xml
@@ -45,6 +45,12 @@ prefer system crypto policy, instead of hardcoding a default.
 
 <change type="feature">
 <para>
+njs support with the basic syntax of JS template literals.
+</para>
+</change>
+
+<change type="feature">
+<para>
 compatibility with OpenSSL 3.
 </para>
 </change>
diff --git a/src/nxt_conf_validation.c b/src/nxt_conf_validation.c
index 09b3be55..e650b44d 100644
--- a/src/nxt_conf_validation.c
+++ b/src/nxt_conf_validation.c
@@ -34,7 +34,7 @@ typedef enum {
 
 typedef enum {
     NXT_CONF_VLDT_REQUIRED  = 1 << 0,
-    NXT_CONF_VLDT_VAR       = 1 << 1,
+    NXT_CONF_VLDT_TSTR      = 1 << 1,
 } nxt_conf_vldt_flags_t;
 
 
@@ -367,7 +367,7 @@ static nxt_conf_vldt_object_t  nxt_conf_vldt_listener_members[] = {
         .name       = nxt_string("pass"),
         .type       = NXT_CONF_VLDT_STRING,
         .validator  = nxt_conf_vldt_pass,
-        .flags      = NXT_CONF_VLDT_VAR,
+        .flags      = NXT_CONF_VLDT_TSTR,
     }, {
         .name       = nxt_string("application"),
         .type       = NXT_CONF_VLDT_STRING,
@@ -652,7 +652,7 @@ static nxt_conf_vldt_object_t  nxt_conf_vldt_pass_action_members[] = {
         .name       = nxt_string("pass"),
         .type       = NXT_CONF_VLDT_STRING,
         .validator  = nxt_conf_vldt_pass,
-        .flags      = NXT_CONF_VLDT_VAR,
+        .flags      = NXT_CONF_VLDT_TSTR,
     },
 
     NXT_CONF_VLDT_END
@@ -667,7 +667,7 @@ static nxt_conf_vldt_object_t  nxt_conf_vldt_return_action_members[] = {
     }, {
         .name       = nxt_string("location"),
         .type       = NXT_CONF_VLDT_STRING,
-        .flags      = NXT_CONF_VLDT_VAR,
+        .flags      = NXT_CONF_VLDT_TSTR,
     },
 
     NXT_CONF_VLDT_END
@@ -697,7 +697,7 @@ static nxt_conf_vldt_object_t  nxt_conf_vldt_share_action_members[] = {
         .validator  = nxt_conf_vldt_unsupported,
         .u.string   = "chroot",
 #endif
-        .flags      = NXT_CONF_VLDT_VAR,
+        .flags      = NXT_CONF_VLDT_TSTR,
     }, {
         .name       = nxt_string("follow_symlinks"),
         .type       = NXT_CONF_VLDT_BOOLEAN,
@@ -1226,8 +1226,9 @@ nxt_int_t
 nxt_conf_validate(nxt_conf_validation_t *vldt)
 {
     nxt_int_t  ret;
+    u_char     error[NXT_MAX_ERROR_STR];
 
-    vldt->tstr_state = nxt_tstr_state_new(vldt->pool);
+    vldt->tstr_state = nxt_tstr_state_new(vldt->pool, 1);
     if (nxt_slow_path(vldt->tstr_state == NULL)) {
         return NXT_ERROR;
     }
@@ -1237,7 +1238,17 @@ nxt_conf_validate(nxt_conf_validation_t *vldt)
         return ret;
     }
 
-    return nxt_conf_vldt_object(vldt, vldt->conf, nxt_conf_vldt_root_members);
+    ret = nxt_conf_vldt_object(vldt, vldt->conf, nxt_conf_vldt_root_members);
+    if (ret != NXT_OK) {
+        return ret;
+    }
+
+    ret = nxt_tstr_state_done(vldt->tstr_state, error);
+    if (ret != NXT_OK) {
+        return nxt_conf_vldt_error(vldt, "%s", error);
+    }
+
+    return NXT_OK;
 }
 
 
@@ -1721,7 +1732,7 @@ nxt_conf_vldt_share_element(nxt_conf_validation_t *vldt,
 
     nxt_conf_get_string(value, &str);
 
-    if (nxt_is_var(&str)) {
+    if (nxt_is_tstr(&str)) {
         return nxt_conf_vldt_var(vldt, &share, &str);
     }
 
@@ -2501,12 +2512,12 @@ nxt_conf_vldt_object(nxt_conf_validation_t *vldt, nxt_conf_value_t *value,
                 continue;
             }
 
-            if (vals->flags & NXT_CONF_VLDT_VAR
+            if (vals->flags & NXT_CONF_VLDT_TSTR
                 && nxt_conf_type(member) == NXT_CONF_STRING)
             {
                 nxt_conf_get_string(member, &var);
 
-                if (nxt_is_var(&var)) {
+                if (nxt_is_tstr(&var)) {
                     ret = nxt_conf_vldt_var(vldt, &name, &var);
                     if (ret != NXT_OK) {
                         return ret;
@@ -3147,7 +3158,7 @@ nxt_conf_vldt_access_log(nxt_conf_validation_t *vldt, nxt_conf_value_t *value,
                                    "The \"path\" string must not be empty.");
     }
 
-    if (nxt_is_var(&conf.format)) {
+    if (nxt_is_tstr(&conf.format)) {
         return nxt_conf_vldt_var(vldt, &format_str, &conf.format);
     }
 
diff --git a/src/nxt_http.h b/src/nxt_http.h
index e29fe60a..a8725d9f 100644
--- a/src/nxt_http.h
+++ b/src/nxt_http.h
@@ -170,7 +170,7 @@ struct nxt_http_request_s {
     void                            *timer_data;
 
     nxt_tstr_query_t                *tstr_query;
-    nxt_var_cache_t                 var_cache;
+    nxt_tstr_cache_t                tstr_cache;
 
     void                            *req_rpc_data;
 
diff --git a/src/nxt_http_request.c b/src/nxt_http_request.c
index 84a67415..73ffd2f0 100644
--- a/src/nxt_http_request.c
+++ b/src/nxt_http_request.c
@@ -282,7 +282,7 @@ nxt_http_request_create(nxt_task_t *task)
 
     task->thread->engine->requests_cnt++;
 
-    r->var_cache.pool = mp;
+    r->tstr_cache.var.pool = mp;
 
     return r;
 
diff --git a/src/nxt_http_return.c b/src/nxt_http_return.c
index 63c7e06f..b50e4ad0 100644
--- a/src/nxt_http_return.c
+++ b/src/nxt_http_return.c
@@ -126,7 +126,7 @@ nxt_http_return(nxt_task_t *task, nxt_http_request_t *r,
         rtcf = r->conf->socket_conf->router_conf;
 
         ret = nxt_tstr_query_init(&r->tstr_query, rtcf->tstr_state,
-                                  &r->var_cache, r, r->mem_pool);
+                                  &r->tstr_cache, r, r->mem_pool);
         if (nxt_slow_path(ret != NXT_OK)) {
             goto fail;
         }
diff --git a/src/nxt_http_route.c b/src/nxt_http_route.c
index 77a59e9c..7081ff7e 100644
--- a/src/nxt_http_route.c
+++ b/src/nxt_http_route.c
@@ -1306,7 +1306,7 @@ nxt_http_pass_var(nxt_task_t *task, nxt_http_request_t *r,
 
     rtcf = r->conf->socket_conf->router_conf;
 
-    ret = nxt_tstr_query_init(&r->tstr_query, rtcf->tstr_state, &r->var_cache,
+    ret = nxt_tstr_query_init(&r->tstr_query, rtcf->tstr_state, &r->tstr_cache,
                               r, r->mem_pool);
     if (nxt_slow_path(ret != NXT_OK)) {
         goto fail;
diff --git a/src/nxt_http_static.c b/src/nxt_http_static.c
index 7143ecd3..68174b9d 100644
--- a/src/nxt_http_static.c
+++ b/src/nxt_http_static.c
@@ -276,7 +276,7 @@ nxt_http_static_iterate(nxt_task_t *task, nxt_http_request_t *r,
         rtcf = r->conf->socket_conf->router_conf;
 
         ret = nxt_tstr_query_init(&r->tstr_query, rtcf->tstr_state,
-                                  &r->var_cache, r, r->mem_pool);
+                                  &r->tstr_cache, r, r->mem_pool);
         if (nxt_slow_path(ret != NXT_OK)) {
             nxt_http_request_error(task, r, NXT_HTTP_INTERNAL_SERVER_ERROR);
             return;
diff --git a/src/nxt_js.c b/src/nxt_js.c
new file mode 100644
index 00000000..52596fe6
--- /dev/null
+++ b/src/nxt_js.c
@@ -0,0 +1,230 @@
+
+/*
+ * Copyright (C) NGINX, Inc.
+ */
+
+#include <nxt_main.h>
+
+
+struct nxt_js_s {
+    uint32_t            index;
+    njs_vm_t            *vm;
+};
+
+
+struct nxt_js_conf_s {
+    nxt_mp_t            *pool;
+    njs_vm_t            *vm;
+    nxt_array_t         *funcs;
+};
+
+
+nxt_js_conf_t *
+nxt_js_conf_new(nxt_mp_t *mp)
+{
+    njs_vm_opt_t   opts;
+    nxt_js_conf_t  *jcf;
+
+    jcf = nxt_mp_zget(mp, sizeof(nxt_js_conf_t));
+    if (nxt_slow_path(jcf == NULL)) {
+        return NULL;
+    }
+
+    jcf->pool = mp;
+
+    njs_vm_opt_init(&opts);
+
+    jcf->vm = njs_vm_create(&opts);
+    if (nxt_slow_path(jcf->vm == NULL)) {
+        return NULL;
+    }
+
+    jcf->funcs = nxt_array_create(mp, 4, sizeof(nxt_str_t));
+    if (nxt_slow_path(jcf->funcs == NULL)) {
+        return NULL;
+    }
+
+    return jcf;
+}
+
+
+nxt_js_t *
+nxt_js_add_tpl(nxt_js_conf_t *jcf, nxt_str_t *str, nxt_bool_t strz)
+{
+    size_t     size;
+    u_char     *p, *start;
+    nxt_js_t   *js;
+    nxt_str_t  *func;
+
+    static nxt_str_t  func_str = nxt_string("function() {"
+                                            "    return ");
+
+    /*
+     * Appending a terminating null character if strz is true.
+     */
+    static nxt_str_t  strz_str = nxt_string(" + '\\x00'");
+
+    size = func_str.length + str->length + 1;
+
+    if (strz) {
+        size += strz_str.length;
+    }
+
+    start = nxt_mp_nget(jcf->pool, size);
+    if (nxt_slow_path(start == NULL)) {
+        return NULL;
+    }
+
+    p = start;
+
+    p = nxt_cpymem(p, func_str.start, func_str.length);
+    p = nxt_cpymem(p, str->start, str->length);
+
+    if (strz) {
+        p = nxt_cpymem(p, strz_str.start, strz_str.length);
+    }
+
+    *p++ = '}';
+
+    js = nxt_mp_get(jcf->pool, sizeof(nxt_js_t));
+    if (nxt_slow_path(js == NULL)) {
+        return NULL;
+    }
+
+    js->vm = jcf->vm;
+
+    func = nxt_array_add(jcf->funcs);
+    if (nxt_slow_path(func == NULL)) {
+        return NULL;
+    }
+
+    func->start = start;
+    func->length = p - start;
+
+    js->index = jcf->funcs->nelts - 1;
+
+    return js;
+}
+
+
+nxt_int_t
+nxt_js_compile(nxt_js_conf_t *jcf)
+{
+    size_t      size;
+    u_char      *p, *start;
+    njs_int_t   ret;
+    nxt_str_t   *func;
+    nxt_uint_t  i;
+
+    size = 2;
+    func = jcf->funcs->elts;
+
+    for (i = 0; i < jcf->funcs->nelts; i++) {
+        size += func[i].length + 1;
+    }
+
+    start = nxt_mp_nget(jcf->pool, size);
+    if (nxt_slow_path(start == NULL)) {
+        return NXT_ERROR;
+    }
+
+    p = start;
+    *p++ = '[';
+
+    func = jcf->funcs->elts;
+
+    for (i = 0; i < jcf->funcs->nelts; i++) {
+        p = nxt_cpymem(p, func[i].start, func[i].length);
+        *p++ = ',';
+    }
+
+    *p++ = ']';
+
+    ret = njs_vm_compile(jcf->vm, &start, p);
+
+    return (ret == NJS_OK) ? NXT_OK : NXT_ERROR;
+}
+
+
+nxt_int_t
+nxt_js_test(nxt_js_conf_t *jcf, nxt_str_t *str, u_char *error)
+{
+    u_char     *start;
+    nxt_str_t  err;
+    njs_int_t  ret;
+    njs_str_t  res;
+
+    start = nxt_mp_nget(jcf->pool, str->length);
+    if (nxt_slow_path(start == NULL)) {
+        return NXT_ERROR;
+    }
+
+    nxt_memcpy(start, str->start, str->length);
+
+    ret = njs_vm_compile(jcf->vm, &start, start + str->length);
+
+    if (nxt_slow_path(ret != NJS_OK)) {
+        (void) njs_vm_retval_string(jcf->vm, &res);
+
+        err.start = res.start;
+        err.length = res.length;
+
+        nxt_sprintf(error, error + NXT_MAX_ERROR_STR, "\"%V\"%Z", &err);
+
+        return NXT_ERROR;
+    }
+
+    return NXT_OK;
+}
+
+
+nxt_int_t
+nxt_js_call(nxt_task_t *task, nxt_js_cache_t *cache, nxt_js_t *js,
+    nxt_str_t *str, void *ctx)
+{
+    njs_vm_t            *vm;
+    njs_int_t           rc, ret;
+    njs_str_t           res;
+    njs_value_t         *array, *value;
+    njs_function_t      *func;
+    njs_opaque_value_t  opaque_value;
+
+    vm = cache->vm;
+
+    if (vm == NULL) {
+        vm = njs_vm_clone(js->vm, ctx);
+        if (nxt_slow_path(vm == NULL)) {
+            return NXT_ERROR;
+        }
+
+        ret = njs_vm_start(vm);
+        if (ret != NJS_OK) {
+            return NXT_ERROR;
+        }
+
+        array = njs_vm_retval(vm);
+
+        cache->vm = vm;
+        cache->array = *array;
+    }
+
+    value = njs_vm_array_prop(vm, &cache->array, js->index, &opaque_value);
+    func = njs_value_function(value);
+
+    ret = njs_vm_call(vm, func, NULL, 0);
+
+    rc = njs_vm_retval_string(vm, &res);
+    if (rc != NJS_OK) {
+        return NXT_ERROR;
+    }
+
+    if (ret != NJS_OK) {
+        nxt_alert(task, "js exception: %V", &res);
+        return NXT_ERROR;
+    }
+
+    str->length = res.length;
+    str->start = res.start;
+
+    return NXT_OK;
+}
diff --git a/src/nxt_js.h b/src/nxt_js.h
new file mode 100644
index 00000000..321041ae
--- /dev/null
+++ b/src/nxt_js.h
@@ -0,0 +1,34 @@
+
+/*
+ * Copyright (C) NGINX, Inc.
+ */
+
+#ifndef _NXT_JS_H_INCLUDED_
+#define _NXT_JS_H_INCLUDED_
+
+#if (NXT_HAVE_NJS)
+
+#include <njs_main.h>
+
+
+typedef struct nxt_js_s       nxt_js_t;
+typedef struct nxt_js_conf_s  nxt_js_conf_t;
+
+
+typedef struct {
+    njs_vm_t            *vm;
+    njs_value_t         array;
+} nxt_js_cache_t;
+
+
+nxt_js_conf_t *nxt_js_conf_new(nxt_mp_t *mp);
+nxt_js_t *nxt_js_add_tpl(nxt_js_conf_t *jcf, nxt_str_t *str, nxt_bool_t strz);
+nxt_int_t nxt_js_compile(nxt_js_conf_t *jcf);
+nxt_int_t nxt_js_test(nxt_js_conf_t *jcf, nxt_str_t *str, u_char *error);
+nxt_int_t nxt_js_call(nxt_task_t *task, nxt_js_cache_t *cache, nxt_js_t *js,
+    nxt_str_t *str, void *ctx);
+
+
+#endif /* NXT_HAVE_NJS */
+
+#endif /* _NXT_JS_H_INCLUDED_ */
diff --git a/src/nxt_router.c b/src/nxt_router.c
index 3ad78fa4..26aa9fb1 100644
--- a/src/nxt_router.c
+++ b/src/nxt_router.c
@@ -1060,7 +1060,7 @@ nxt_router_temp_conf(nxt_task_t *task)
 
     rtcf->mem_pool = mp;
 
-    rtcf->tstr_state = nxt_tstr_state_new(mp);
+    rtcf->tstr_state = nxt_tstr_state_new(mp, 0);
     if (nxt_slow_path(rtcf->tstr_state == NULL)) {
         goto fail;
     }
@@ -2042,6 +2042,11 @@ nxt_router_conf_create(nxt_task_t *task, nxt_router_temp_conf_t *tmcf,
         }
     }
 
+    ret = nxt_tstr_state_done(rtcf->tstr_state, NULL);
+    if (nxt_slow_path(ret != NXT_OK)) {
+        goto fail;
+    }
+
     nxt_queue_add(&deleting_sockets, &router->sockets);
     nxt_queue_init(&router->sockets);
 
diff --git a/src/nxt_router_access_log.c b/src/nxt_router_access_log.c
index 9da366f4..ccbddb96 100644
--- a/src/nxt_router_access_log.c
+++ b/src/nxt_router_access_log.c
@@ -161,7 +161,7 @@ nxt_router_access_log_writer(nxt_task_t *task, nxt_http_request_t *r,
         rtcf = r->conf->socket_conf->router_conf;
 
         ret = nxt_tstr_query_init(&r->tstr_query, rtcf->tstr_state,
-                                  &r->var_cache, r, r->mem_pool);
+                                  &r->tstr_cache, r, r->mem_pool);
         if (nxt_slow_path(ret != NXT_OK)) {
             return;
         }
diff --git a/src/nxt_tstr.c b/src/nxt_tstr.c
index dff61952..fd01797c 100644
--- a/src/nxt_tstr.c
+++ b/src/nxt_tstr.c
@@ -9,12 +9,22 @@
 typedef enum {
     NXT_TSTR_CONST = 0,
     NXT_TSTR_VAR,
+#if (NXT_HAVE_NJS)
+    NXT_TSTR_JS,
+#endif
 } nxt_tstr_type_t;
 
 
 struct nxt_tstr_s {
     nxt_str_t           str;
-    nxt_var_t           *var;
+
+    union {
+        nxt_var_t       *var;
+#if (NXT_HAVE_NJS)
+        nxt_js_t        *js;
+#endif
+    } u;
+
     nxt_tstr_flags_t    flags;
     nxt_tstr_type_t     type;
 };
@@ -24,7 +34,7 @@ struct nxt_tstr_query_s {
     nxt_mp_t            *pool;
 
     nxt_tstr_state_t    *state;
-    nxt_var_cache_t     *cache;
+    nxt_tstr_cache_t    *cache;
 
     nxt_uint_t          waiting;
     nxt_uint_t          failed;   /* 1 bit */
@@ -37,8 +47,12 @@ struct nxt_tstr_query_s {
 };
 
 
+#define nxt_tstr_is_js(str)                                         \
+    nxt_strchr_start(str, '`')
+
+
 nxt_tstr_state_t *
-nxt_tstr_state_new(nxt_mp_t *mp)
+nxt_tstr_state_new(nxt_mp_t *mp, nxt_bool_t test)
 {
     nxt_tstr_state_t  *state;
 
@@ -48,12 +62,20 @@ nxt_tstr_state_new(nxt_mp_t *mp)
     }
 
     state->pool = mp;
+    state->test = test;
 
     state->var_fields = nxt_array_create(mp, 4, sizeof(nxt_var_field_t));
     if (nxt_slow_path(state->var_fields == NULL)) {
         return NULL;
     }
 
+#if (NXT_HAVE_NJS)
+    state->jcf = nxt_js_conf_new(mp);
+    if (nxt_slow_path(state->jcf == NULL)) {
+        return NULL;
+    }
+#endif
+
     return state;
 }
 
@@ -88,18 +110,38 @@ nxt_tstr_compile(nxt_tstr_state_t *state, nxt_str_t *str,
 
     tstr->flags = flags;
 
-    p = nxt_memchr(str->start, '$', str->length);
+    if (nxt_tstr_is_js(str)) {
+
+#if (NXT_HAVE_NJS)
+
+        nxt_str_t  tpl;
 
-    if (p != NULL) {
-        tstr->type = NXT_TSTR_VAR;
+        tstr->type = NXT_TSTR_JS;
 
-        tstr->var = nxt_var_compile(&tstr->str, state->pool, state->var_fields);
-        if (nxt_slow_path(tstr->var == NULL)) {
+        nxt_tstr_str(tstr, &tpl);
+
+        tstr->u.js = nxt_js_add_tpl(state->jcf, &tpl, strz);
+        if (nxt_slow_path(tstr->u.js == NULL)) {
             return NULL;
         }
 
+#endif
+
     } else {
-        tstr->type = NXT_TSTR_CONST;
+        p = memchr(str->start, '$', str->length);
+
+        if (p != NULL) {
+            tstr->type = NXT_TSTR_VAR;
+
+            tstr->u.var = nxt_var_compile(&tstr->str, state->pool,
+                                          state->var_fields);
+            if (nxt_slow_path(tstr->u.var == NULL)) {
+                return NULL;
+            }
+
+        } else {
+            tstr->type = NXT_TSTR_CONST;
+        }
     }
 
     return tstr;
@@ -109,7 +151,46 @@ nxt_tstr_compile(nxt_tstr_state_t *state, nxt_str_t *str,
 nxt_int_t
 nxt_tstr_test(nxt_tstr_state_t *state, nxt_str_t *str, u_char *error)
 {
-    return nxt_var_test(str, state->var_fields, error);
+    u_char  *p;
+
+    if (nxt_tstr_is_js(str)) {
+#if (NXT_HAVE_NJS)
+        return nxt_js_test(state->jcf, str, error);
+
+#else
+        nxt_sprintf(error, error + NXT_MAX_ERROR_STR,
+                    "Unit is built without support of njs: "
+                    "\"--njs\" ./configure option is missing.");
+        return NXT_ERROR;
+#endif
+
+    } else {
+        p = memchr(str->start, '$', str->length);
+
+        if (p != NULL) {
+            return nxt_var_test(str, state->var_fields, error);
+        }
+    }
+
+    return NXT_OK;
+}
+
+
+nxt_int_t
+nxt_tstr_state_done(nxt_tstr_state_t *state, u_char *error)
+{
+#if (NXT_HAVE_NJS)
+    if (!state->test) {
+        nxt_int_t  ret;
+
+        ret = nxt_js_compile(state->jcf);
+        if (nxt_slow_path(ret != NXT_OK)) {
+            return NXT_ERROR;
+        }
+    }
+#endif
+
+     return NXT_OK;
 }
 
 
@@ -133,7 +214,7 @@ nxt_tstr_str(nxt_tstr_t *tstr, nxt_str_t *str)
 
 nxt_int_t
 nxt_tstr_query_init(nxt_tstr_query_t **query_p, nxt_tstr_state_t *state,
-    nxt_var_cache_t *cache, void *ctx, nxt_mp_t *mp)
+    nxt_tstr_cache_t *cache, void *ctx, nxt_mp_t *mp)
 {
     nxt_tstr_query_t  *query;
 
@@ -172,11 +253,24 @@ nxt_tstr_query(nxt_task_t *task, nxt_tstr_query_t *query, nxt_tstr_t *tstr,
         return;
     }
 
-    ret = nxt_var_interpreter(task, query->cache, tstr->var, val, query->ctx,
-                              tstr->flags & NXT_TSTR_LOGGING);
-    if (nxt_slow_path(ret != NXT_OK)) {
-        query->failed = 1;
-        return;
+    if (tstr->type == NXT_TSTR_VAR) {
+        ret = nxt_var_interpreter(task, &query->cache->var, tstr->u.var, val,
+                                  query->ctx, tstr->flags & NXT_TSTR_LOGGING);
+
+        if (nxt_slow_path(ret != NXT_OK)) {
+            query->failed = 1;
+            return;
+        }
+
+    } else {
+#if (NXT_HAVE_NJS)
+        ret = nxt_js_call(task, &query->cache->js, tstr->u.js, val, query->ctx);
+
+        if (nxt_slow_path(ret != NXT_OK)) {
+            query->failed = 1;
+            return;
+        }
+#endif
     }
 
     if (tstr->flags & NXT_TSTR_STRZ) {
@@ -188,7 +282,7 @@ nxt_tstr_query(nxt_task_t *task, nxt_tstr_query_t *query, nxt_tstr_t *tstr,
 
     nxt_tstr_str(tstr, &str);
 
-    nxt_debug(task, "tstr: \"%V\" -> \"%V\"", &str, val);
+    nxt_debug(task, "tstr query: \"%V\", result: \"%V\"", &str, val);
 #endif
 }
 
diff --git a/src/nxt_tstr.h b/src/nxt_tstr.h
index 692b9d28..0cc24292 100644
--- a/src/nxt_tstr.h
+++ b/src/nxt_tstr.h
@@ -7,6 +7,8 @@
 #define _NXT_TSTR_H_INCLUDED_
 
 
+#include <nxt_js.h>
+
 typedef struct nxt_tstr_s        nxt_tstr_t;
 typedef struct nxt_tstr_query_s  nxt_tstr_query_t;
 
@@ -14,25 +16,38 @@ typedef struct nxt_tstr_query_s  nxt_tstr_query_t;
 typedef struct {
     nxt_mp_t            *pool;
     nxt_array_t         *var_fields;
+#if (NXT_HAVE_NJS)
+    nxt_js_conf_t       *jcf;
+#endif
+    uint8_t             test;  /* 1 bit */
 } nxt_tstr_state_t;
 
 
+typedef struct {
+    nxt_var_cache_t     var;
+#if (NXT_HAVE_NJS)
+    nxt_js_cache_t      js;
+#endif
+} nxt_tstr_cache_t;
+
+
 typedef enum {
     NXT_TSTR_STRZ       = 1 << 0,
     NXT_TSTR_LOGGING    = 1 << 1,
 } nxt_tstr_flags_t;
 
 
-nxt_tstr_state_t *nxt_tstr_state_new(nxt_mp_t *mp);
+nxt_tstr_state_t *nxt_tstr_state_new(nxt_mp_t *mp, nxt_bool_t test);
 nxt_tstr_t *nxt_tstr_compile(nxt_tstr_state_t *state, nxt_str_t *str,
     nxt_tstr_flags_t flags);
 nxt_int_t nxt_tstr_test(nxt_tstr_state_t *state, nxt_str_t *str, u_char *error);
+nxt_int_t nxt_tstr_state_done(nxt_tstr_state_t *state, u_char *error);
 
 nxt_bool_t nxt_tstr_is_const(nxt_tstr_t *tstr);
 void nxt_tstr_str(nxt_tstr_t *tstr, nxt_str_t *str);
 
 nxt_int_t nxt_tstr_query_init(nxt_tstr_query_t **query_p,
-    nxt_tstr_state_t *state, nxt_var_cache_t *cache, void *ctx,
+    nxt_tstr_state_t *state, nxt_tstr_cache_t *cache, void *ctx,
     nxt_mp_t *mp);
 void nxt_tstr_query(nxt_task_t *task, nxt_tstr_query_t *query, nxt_tstr_t *tstr,
     nxt_str_t *val);
@@ -42,4 +57,23 @@ void nxt_tstr_query_handle(nxt_task_t *task, nxt_tstr_query_t *query,
     nxt_bool_t failed);
 
 
+nxt_inline nxt_bool_t
+nxt_is_tstr(nxt_str_t *str)
+{
+    u_char  *p;
+
+    p = memchr(str->start, '`', str->length);
+    if (p != NULL) {
+        return 1;
+    }
+
+    p = memchr(str->start, '$', str->length);
+    if (p != NULL) {
+        return 1;
+    }
+
+    return 0;
+}
+
+
 #endif /* _NXT_TSTR_H_INCLUDED_ */
diff --git a/src/nxt_var.h b/src/nxt_var.h
index 2c6f13bd..4f30a002 100644
--- a/src/nxt_var.h
+++ b/src/nxt_var.h
@@ -39,13 +39,6 @@ typedef struct {
 } nxt_var_cache_t;
 
 
-nxt_inline nxt_bool_t
-nxt_is_var(nxt_str_t *str)
-{
-    return (memchr(str->start, '$', str->length) != NULL);
-}
-
-
 nxt_int_t nxt_var_register(nxt_var_decl_t *decl, size_t n);
 nxt_int_t nxt_var_index_init(void);