stuff.js

/*jshint node: true */
var sourceMap = require('source-map'),
    fs        = require('fs');


function main() {
    var newMapping = new sourceMap.SourceMapGenerator();
    var source = new sourceMap.SourceMapConsumer(require('./tangram.debug.js.map.json'));

/*

map.addMapping({
  generated: {
    line: 10,
    column: 35
  },
  source: "foo.js",
  original: {
    line: 33,
    column: 2
  },
  name: "christopher"
});

{ source: '/home/ivan/dev/mapzen/tangram/node_modules/gl-matrix/dist/gl-matrix.js',
  generatedLine: 1896,
  generatedColumn: 0,
  originalLine: 1895,
  originalColumn: 0,
  name: undefined }


*/



    source.eachMapping(function (oldMapping) {
        var mapping = {
            source: oldMapping.source,
            generated: {
                line: oldMapping.generatedLine,
                column: oldMapping.generatedColumn
            },
            original: {
                line: oldMapping.originalLine,
                column: oldMapping.originalColumn
            }
        };
        newMapping.addMapping(mapping);

    }, this, sourceMap.SourceMapConsumer.ORIGINAL_ORDER);

    fs.writeFileSync('test.json', newMapping.toString());
}


main();