Just a basic node script which saves the AST of JS code in a file.

simple AST creation

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

var code = `let array = [1,2,'b'];
`;

var ast = espree.parse(code, {
    ecmaVersion: 6
});

console.log("writing ast to ast.json")
fs.writeFile("ast.json", JSON.stringify(ast, null, 4), function(err) {
    if(err) return err;
});