theosotr/async-tajs

Static Analysis for Asynchronous JavaScript Programs.

Async TAJS

This is an extension of TAJS (https://github.com/cs-au-dk/TAJS) that provides support for asynchronous JavaScript programs.

The details of the extension are described in the ECOOP'19 paper "Static Analysis for Asynchronous JavaScript Programs".

How to build and run the tool

Make sure you clone not only the TAJS repository but also the submodules, for example by running

git submodule update --init --recursive

The simplest way to build TAJS is to run Ant:

ant

This will build two jar files: dist/tajs.jar (contains only TAJS itself) and dist/tajs-all.jar (includes the relevant extra libraries).

You can now run the analysis as, for example:

java -jar dist/tajs-all.jar test-resources/src/google/richards.js

or

java -jar dist/tajs-all.jar test-resources/src/chromeexperiments/3ddemo.html

Analyzing an asynchronous program

var t;
function foo() {
    if (TAJS_make('AnyBool')) {
        return Promise.resolve('foo').then(
            function fun2() {
                t = {bar: 1};
                return 'foo';
            }
        ).then(function fun3(value) {
            TAJS_assertEquals(value, 'foo');
            throw 'baz';
        });
    } else {
        return Promise.resolve({
            then: function fun4(res) {
                TAJS_dumpValue('thenable exec');
                t = {bar : 1};
                res('bar');
            }
        });
    }
}


var x = Promise.resolve('bar');
x
    .then(function fun1(value) {
        TAJS_assertEquals(value, 'bar');
        return foo();
    })
    .then(function fun5(value) {
        t.bar; // no error;
        TAJS_assertEquals(value, 'bar');
    })
    .catch(function fun6(value) {
        // This error is propagated from fun3.
        TAJS_dumpValue(value);
    });

Analyzing this program with async TAJS produces the following callback graph:

The deRej() and deFul() functions are the default promise-related functions used for promise rejection and fulfillment respectively, as described in ECMAScript Specification.