ast-transform.js

var acorn = require('acorn'); // parser
var esrecurse = require('esrecurse'); // walker
var t = require('ast-types').builders; // ast types
var escodegen = require('escodegen'); // generator

/* parse -> walk -> types -> generate */

var ast = acorn.parse('var x = 23 * 576;'); // code -> ast

// traverse ast
esrecurse.visit(ast, {

  VariableDeclaration(node) {

    node.declarations.forEach(function(d) {

      var left = d.init.left.value; // 23
      var right = d.init.right.value; // 576
      var operator = d.init.operator; // *

      // BinaryExpression -> Literal
      d.init = t.literal(eval(left + operator + right)); // 23 * 576
    });

    node.kind = 'const'; // var -> const
  }
});

var code = escodegen.generate(ast); // ast -> code

console.log(code); // const x = 13248;