Nested JSON: How to add (push) new items to an object?

Question

I\'m just starting with Arrays, Objects, and JSON - so hopefully there\'s just something simple I\'m overlooking here. I\'m encountering an error when attempting to

Answer 1

You can achieve this using Lodash _.assign function.

library[title] = _.assign({}, {'foregrounds': foregrounds }, {'backgrounds': backgrounds });

// This is my JSON object generated from a database
var library = {
  "Gold Rush": {
    "foregrounds": ["Slide 1", "Slide 2", "Slide 3"],
    "backgrounds": ["1.jpg", "", "2.jpg"]
  },
  "California": {
    "foregrounds": ["Slide 1", "Slide 2", "Slide 3"],
    "backgrounds": ["3.jpg", "4.jpg", "5.jpg"]
  }
}

// These will be dynamically generated vars from editor
var title = "Gold Rush";
var foregrounds = ["Howdy", "Slide 2"];
var backgrounds = ["1.jpg", ""];

function save() {

  // If title already exists, modify item
  if (library[title]) {

    // override one Object with the values of another (lodash)
    library[title] = _.assign({}, {
      'foregrounds': foregrounds
    }, {
      'backgrounds': backgrounds
    });
    console.log(library[title]);

    // Save to Database. Then on callback...
    // console.log('Changes Saved to ' + title + '');
  }

  // If title does not exist, add new item
  else {
    // Format it for the JSON object
    var item = ('"' + title + '" : {"foregrounds" : ' + foregrounds + ',"backgrounds" : ' + backgrounds + '}');

    // THE PROBLEM SEEMS TO BE HERE??
    // Error: "Result of expression 'library.push' [undefined] is not a function"
    library.push(item);

    // Save to Database. Then on callback...
    console.log('Added: ' + title + '');
  }
}

save();