jssi's Introduction

JSSI

JSSI is a JavaScript to TypeScript compiler.

Installation

Make sure you have node.js installed

git clone https://github.com/pitust/jssi
cd jssi
npm install
npm link

How does it work?

It works by removing some JS constructs, such as loops, adding variable and function call tracers. So for example this:

let i = 0;
export function randomCall() {
  out(i++);
}
out(2);
randomCall();

is transpiled to this (without prepended libJSSI, the runtime):

let i = __varset("0", 0, "0");

function randomCall() {
  let __intcfncid = __funcCalled(this, 0x0, arguments);
  out(i++);
  __returning(__intcfncid);
}

out(2);
randomCall();
__passRetev({vm, fnm});

__passRetev is defined in interp.js Note that by the i++ there is no __varset. This is because pre- and post- incrimination HAVE to input numbers, so their result HAS to be number.

Usage

Usage: jssi <input> [flags]
    Flags:
        -o, --output <output>     Output File
        -D, --defs <deffile>      Definiton File
        -T, --typemap <typemap>   Type Map
        -E, --save-sandbox        Print code sent to the sandbox

Input and Output are fairly self-explanatory. Definition file is YAML with following contents:

<function name>:
  args:
    - <type> <name>
  rets: <return type>

The type map is JSON:

{
    "types": {
        // Here key is the source type and value is mapped type
    },
    // The prefix and suffix is ignored for undefined
    "suffix": " | null",
    "prefix": ""
}

The Save Sandbox option will save the code executed in the sandbox to a file. The file name is determined by removing the file extension and adding .sbx.js.

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