README.md

The file mapshaper-browserify.js is generated from the mapshaper node module (see LICENSE file) using the browserify node module, as suggested in the V8 vignette:

The license for mapshaper and its dependencies, as well as their licenses, are listed in node_packages.csv.

npm install -g browserify
npm install mapshaper
echo "global.mapshaper = require('mapshaper');" > in.js
browserify in.js -o inst/mapshaper/mapshaper-browserify.js
rm in.js

setTimout and setImmediate

Because the functions setTimeout and setImmediate are not available in the V8 engine, the definition of utils.reduceAsync (approximately line 18000 in the browserified file) must be slightly modified to avoid them. Thanks to @timelyportfolio for figuring this out:

utils.reduceAsync = function(arr, memo, iter, done) {
  // For V8 in R: commented out the next line wich looks for setTimeout / setImmediate
  //var call = typeof setImmediate == 'undefined' ? setTimeout : setImmediate;
  var i=0;
  next(null, memo);

  function next(err, memo) {
    // Detach next operation from call stack to prevent overflow
    // Don't use setTimeout(, 0) if setImmediate is available
    // (setTimeout() can introduce a long delay if previous operation was slow,
    //    as of Node 0.10.32 -- a bug?)
    if (err) {
      return done(err, null);
    }
    // For V8 in R: comment out the `call` call, and replace with anonymous function
    /*
    call(function() {
      if (i < arr.length === false) {
        done(null, memo);
      } else {
        iter(memo, arr[i++], next);
      }
    }, 0);
    */
    (function() {
      if (i < arr.length === false) {
        done(null, memo);
      } else {
        iter(memo, arr[i++], next);
      }
    })();
  }
};