map json keys to javascript object

Question

I need to parse a json file into a javascript object. I'm using GCC (Closure Compiler) which might mangle my object names, so I need to refer to the json keys as strings when importing or exporting the json file.

ie importing:

var jsonobj = JSON.parse(json_object_text);
myobj.member1 = jsonobj['Key 1'];
myobj.member2 = jsonobj['Key 2'];

and exporting:

jsonobj['Key 1'] = myobj.member1;
jsonobj['Key 2'] = myobj.member2;
var json_object_text = JSON.stringify(jsonobj);

But doing that is tedious. And I would like to only define the keys as text strings once.

So I tried to define a constant object which is kind of mapping from javascript object to the json schema.

// Schema definition for import/export of confc.json.
/** @const */ var dbs = {
    $schema: '$schema',
    $seq: '$seq',
    channel: {
      key: 'chan',
      id: 'id',
      name: 'txt',
      value: 'val'
    }
}

But then I still had to do a tedious import/export function:

    export_db: function (db) {
      return db && {
        [dbs.$schema]: db.$schema,
        [dbs.$seq]: db.$seq,
        [dbs.channel.key]: db.channel.map(function (e, i) {
          var s = dbs.channel; // schema object
          return {
            [s.id]: util.toInt(e.id),
            [s.name]: e.name,
            [s.value]: e.value
          };
        }),

    import_db: function (js) {
      js = js || {};
      // wrapper for .map() function which works if array is undefined.
      function dbmap(arr_in, func) {
        arr_in = arr_in || [];
        return arr_in.map(func);
      }
      return {
        $schema: js[dbs.$schema],
        $seq: js[dbs.$seq],
        channel: dbmap(js[dbs.channel.key], function (e, i) {
          var s = dbs.channel;
          return {
            id: e[s.id],
            name: e[s.name],
            value: e[s.value]
          };
        }),

This seems to work OK, but would someone please show me a cleaner way to do this?

I would like to use an object prototype/constructor like in the examples given here . But I don't see any examples that take into account how GCC might mangle the objects member names. Also I have nested objects (no functions, just text and numbers).

Answer 1

JSON is inherently already in object format (JSON = JavaScript Object Notation).

var jsonobj = JSON.parse(json_object_text) should be all you need to access the object you just created called jsonobj . Any members of that object are accessible just as if you had defined them in an constructor or anywhere else. Is there a reason you're remapping it to a different object?

Answer 2

If the data source is external, or if you need to share the data externally, the way that Closure supports this via externs and @export annotations . User contributed externs are a great source for examples.

It might look like this, depending on your environment;

// externs/config.js

/**
 * @typedef {{
 *   foo: (string|undefined),
 *   [...]
 * }}
 */
Bar.Config;

/**
 * @typedef {{
 *   bar: (string|undefined),
 *   [...]
 * }}
 */
Bar.Output;

// main.js

/**
 * @param {Bar.Config} config 
 * @return {Bar.Output}
 */
const bar = function(config) {
//  [...]
  return output;
};