scoper

modify nested scope at runtime

example

modify

Given this simple source:

var x = 3;

setInterval(function () {
    console.log(100 * x);
}, 500);

we can modify the values of the variable x and the constant 100 at runtime:

var fs = require('fs');
var scoper = require('scoper');

var src = fs.readFileSync(__dirname + '/source/simple.js', 'utf8');
var c = Function('return ' + scoper(src))();
c.run();

setInterval(function () {
    c.literal['arguments.0'][0] += 10;
}, 500);

setTimeout(function () {
    c.scope[''].x = 11;
}, 2000);

$ node example/simple.js
300
330
360
390
1540
1650
1760
1870
1980
2090
^C

attributes

Given some source:

var x = 5;

function foo (n) {
    var y = n + x + 100;
    
    return (function bar () {
        var z = 6;
        var f = function () {
            var q = y * 10;
            var x = z + 2;
            return q + x;
        };
        return f(z);
    })();
}

setInterval(function () {
    console.log(foo(32));
}, 500);

the attribute object looks like:

$ node example/attr
{ scope: 
   { '': {},
     'body.1': {},
     'body.1.callee': {},
     'body.1.callee.init': {},
     'body.1.callee.right': {},
     'arguments.0': {} },
  function: 
   { 'body.1.callee.right': [Function],
     'body.1.callee': [Function: bar],
     'body.1': [Function: foo],
     'arguments.0': [Function] },
  literal: 
   { '': [ 5, 500 ],
     'body.1': [ 100 ],
     'body.1.callee': [ 6 ],
     'body.1.callee.init': [ 10, 2 ],
     'arguments.0': [ 32 ] },
  patch: [Function],
  run: [Function] }

methods

var scoper = require('scoper')

var newSrc = scoper(src, opts)

Return a string that rewrites src to add scoping instrumentation hooks.

Optionally:

opts.names - an object mapping scope, function, and literal keys to internal ids to use for names in the rewritten source. By default, these names are randomly generated.

var c = Function('return ' + newSrc)()

Create a new scoper context c from the javascript source string newSrc returned by scoper().

c.run()

Run the source. You can run the source as many times as you like. You can modify the scope attributes before, after, or during a run.

c.patch(ctx)

Patch the current context with a new context ctx. ctx should have one or more attributes ctx.scope, ctx.function and ctx.literal to replace the internal attributes of the current object.

attributes

c.scope

All the variables are kept in this object.

c.function

Copies of all functions are kept here so you can modify the functions at runtime.

c.literal

The literal number, string, boolean, and regex values are stored in this object.

install

With npm do:

npm install scoper

license

MIT