clj-rhino

a nice wrapper to handle rhino from clojure

who?

marianoguerra

why?

the java api for rhino is not really nice

how?

go to clojars page for instructions:

https://clojars.org/org.marianoguerra/clj-rhino

you can see the tests for some usage, here are some REPL examples::

    user=> (require '[clj-rhino :as js])
    nil
    user=> (def sc (js/new-safe-scope))
    #'user/sc
    user=> (js/eval sc "1 + 1")
    2
    user=> (js/eval sc "a = 1 + 1")
    2
    user=> (js/get sc "a")
    2
    user=> (js/get sc "b")
    #<UniqueTag org.mozilla.javascript.UniqueTag@172897f: NOT_FOUND>
    user=> (js/undefined? (js/get sc "b"))
    true
    user=> (js/get sc "b" :w00t?)
    :w00t?
    user=> (js/defined? (js/get sc "b"))
    false
    user=> (js/set! sc "b" 42)
    nil
    user=> (js/defined? (js/get sc "b"))
    true
    user=> (js/get sc "b" :w00t?)
    42
    user=> (js/eval sc "a = {name: 'spongebob'}")
    #<NativeObject [object Object]>
    user=> (js/get-in sc [:a :name])
    "spongebob"
    user=> (js/get-in sc [:a :age])
    #<UniqueTag org.mozilla.javascript.UniqueTag@172897f: NOT_FOUND>
    user=> (js/get-in sc [:a :age] :dont-know)
    :dont-know
    user=> (def compiled-fun (js/compile-function sc "function (a, b) { return a + b; }" :filename "foo.js"))
    #'user/compiled-fun
    user=> (js/set! sc "add" compiled-fun)
    nil
    user=> (js/eval sc "add(1, 3)")
    4.0

handy convertions::

    user=> (def get-field (js/compile-function sc "function getField(obj, field) { return obj[field]; }"))
    #'user/get-field

    user=> (js/set! sc "getField" get-field)
    nil

    user=> (js/set! sc "obj" (js/with-context #(js/to-js {:name "spongebob"} sc %)))
    nil

    user=> (js/eval sc "getField(obj, 'name')")
    "spongebob"

    user=> (js/eval sc "o = {name: 'spongebob', friends: ['patrick', 'sandy']};")
    #<NativeObject [object Object]>

    user=> (js/from-js (js/eval sc "o = {name: 'spongebob', friends: ['patrick', 'sandy']};"))
    {:friends ["patrick" "sandy"], :name "spongebob"}

exposing clojure functions to rhino::

    user=> (require '[clj-rhino :as js])
    nil

    user=> (defn add [ctx scope this [a b]] (+ a b))
    #'user/add

    user=> (def scope (js/new-safe-scope))
    #'user/scope

    user=> (js/set! scope "add" (js/make-fn add))
    nil

    user=> (js/eval scope "add(1, 2)")
    3.0

exposing objects with functions::

    user=> (require '[clj-rhino :as js])
    nil

    user=> (defn add [ctx scope this [a b]] (+ a b))
    #'user/add

    user=> (defn mul [ctx scope this [a b]] (* a b))
    #'user/mul

    user=> (def scope (js/new-safe-scope))
    #'user/scope

    user=> (def api {:add add :multiply mul})
    #'user/api

    user=> (js/with-context (fn [ctx]
      #_=>   (js/set! scope "api" (js/to-js api scope ctx))
      #_=>   (js/eval scope "api.add(1, 2) + api.multiply(2, 3)")))
    9.0

or if you don't need the internal parameters::

    (js/with-context
      (fn [ctx]
        (let [scope (js/new-safe-scope)
              add (fn [a b] (+ a b))]
          
          (js/set! scope "add" (js/wrap-plain-fn add))
          (js/eval scope "add(1, 2)") 3.0)))

execute code with timeout::

    (def scope (js/new-safe-scope))
    (js/eval-timeout scope "while (true);" 1000)

    ; will throw a Error exception

call function with timeout::

    user=> (def f (js/compile-function scope "function () { while(true); }"))
    #'user/f
    user=> (js/call-timeout scope f 1000)
    TimeOutError
    org.marianoguerra.rhino.TimedContextFactory.observeInstructionCount
    (TimedContextFactory.java:47)

    ; function that doesn't timeout
    user=> (def f1 (js/compile-function scope "function (a, b) { return a +
    b; }"))
    #'user/f1
    user=> (js/call-timeout scope f1 1000 1 3)
    4.0