added js and js/hello

sheets/_js/hello

@@ -0,0 +1,16 @@
+// JavaScript is available in most web browsers
+// For standalong JavaScript usage
+// install Node.js or SpiderMonkey
+
+// Works with web browsers
+document.write("Hello world!");
+
+// Works with NJS (0.2.5), Rhino, SpiderMonkey
+print('Hello world!');
+
+// Works with JScript
+WScript.Echo("Hello world!");
+
+// Works with Node.js
+console.log("Hello world!")
+

sheets/js

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+# js
+#
+# JavaScript often abbreviated as "JS", is a high-level, dynamic, untyped, interpreted run-time language.
+# It has been standardized in the ECMAScript language specification.
+#
+# js is a JavaScript shell, part of SpiderMonkey
+# to install spidermonkey: (in Debian) apt-get install libmozjs-24-bin
+
+# Run the shell in interactive mode
+js
+
+# Run the JavaScript code in the file hello.js
+js hello.js
+
+# Run hello.js then drop into the interactive shell
+js -f hello.js -i
+
+# See also:
+#   JavaScript language cheat sheets at /js/
+#   list of pages:      /js/:list
+#   learn JavaScript:   /js/:learn
+#   JS one-liners:      /js/1line
+#   JS weirdness:       /js/weirdness
+#   search in pages:    /js/~keyword