walk ast example

module.exports = function(grunt) {
  grunt.registerTask('walk-ast', function() {
    grunt.log.writeln('walking');
    var file = require('file');
    var uglify = require('uglify-js');
    var result = [];

    function walkAST(node) {
      if (node instanceof uglify.AST_If) {
        if (node.condition) {
          result.push(node.condition.start.value);
        }
      }
    } 

    astRoot = uglify.parse(grunt.file.read('app.js'));
    astRoot.walk(new uglify.TreeWalker(walkAST));
    grunt.log.writeln(JSON.stringify(result));
  });
};