There are many JS engines and deployments outside of web browsers. NodeJS is the most popular deployment, but there are many others for special use cases. Some optimize for low overhead and others optimize for ease of embedding within other applications. Since it was designed for ES3 engines, the library can be used in those settings! This demo tries to demonstrate a few alternative deployments.
Some engines provide no default global object. To create a global reference:
var global = (function(){ return this; }).call(null);iOS and OSX ship with the JavaScriptCore framework, enabling easy JS access from Swift and Objective-C. Hybrid function invocation is tricky, but explicit data passing is straightforward.
Binary strings can be passed back and forth using String.Encoding.ascii.
Nashorn ships with Java 8. It includes a command-line tool jjs for running JS
scripts. It is somewhat limited but does offer access to the full Java runtime.
jjs does not provide a CommonJS require implementation. This demo uses a
shim
and manually requires the library.
The Java nio API provides the Files.readAllBytes method to read a file into
a byte array. To use in XLSX.read, the demo copies the bytes into a plain JS
array and calls XLSX.read with type "array".
Rhino is an ES3+ engine written in Java. The
SheetJSRhino class and com.sheetjs package show a complete JAR deployment,
including the full XLSX source.
Due to code generation errors, optimization must be disabled:
Context context = Context.enter();
context.setOptimizationLevel(-1);ChakraCore is an embeddable JS engine written in C++. The library and binary
distributions include a command-line tool chakra for running JS scripts.
The simplest way to interop with the engine is to pass Base64 strings. The make target builds a very simple payload with the data.
Duktape is an embeddable JS engine written in C. The
amalgamation makes integration extremely simple! It supports Buffer natively:
/* parse a C char array as a workbook object */
duk_push_external_buffer(ctx);
duk_config_buffer(ctx, -1, buf, len);
duk_put_global_string(ctx, "buf");
duk_eval_string_noresult("workbook = XLSX.read(buf, {type:'buffer'});");
/* write a workbook object to a C char array */
duk_eval_string(ctx, "XLSX.write(workbook, {type:'buffer', bookType:'xlsx'})");
duk_size_t sz;
char *buf = (char *)duk_get_buffer_data(ctx, -1, sz);
duk_pop(ctx);