Combine or merge JSON on node.js without jQuery

Underscore's extend is the easiest and quickest way to achieve this, like James commented.

Here's an example using underscore:

var _ = require('underscore'), // npm install underscore to install
  object1 = {name: "John"},
  object2 = {location: "San Jose"};

var target = _.extend(object1, object2);

object 1 will get the properties of object2 and be retured and assigned to target. You could do it like this as well, depending on whether you mind object1 being modified:

var target = {};
_.extend(target, object1, object2);

There is also the built in util._extend:

var extend = require('util')._extend
var o = extend({}, {name: "John"});
extend(o,  {location: "San Jose"});

It doesn't do a deep copy and only allows two arguments at a time, but is built in. I saw this mentioned on a question about cloning objects in node: http://stackoverflow.com/a/15040626.

A normal loop?

function extend(target) {
    var sources = [].slice.call(arguments, 1);
    sources.forEach(function (source) {
        for (var prop in source) {
            target[prop] = source[prop];
        }
    });
    return target;
}

var object3 = extend({}, object1, object2);

That's a basic starting point. You may want to add things like a hasOwnProperty check, or add some logic to handle the case where multiple source objects have a property with the same identifier.

Here's a working example.

Side note: what you are referring to as "JSON" are actually normal JavaScript objects. JSON is simply a text format that shares some syntax with JavaScript.

Here is simple solution, to merge JSON. I did the following.

• Convert each of the JSON to strings using JSON.stringify(object).
• Concatenate all the JSON strings using + operator.
• Replace the pattern /}{/g with ","

• Parse the result string back to JSON object

  var object1 = {name: "John"};
  var object2 = {location: "San Jose"};
  var merged_object = JSON.parse((JSON.stringify(object1) + JSON.stringify(object2)).replace(/}{/g,","))
  

The resulting merged JSON will be

{name: "John", location: "San Jose"}

I see that this thread is too old, but I put my answer here just in logging purposes.

In one of the comments above you mentioned that you wanted to use 'express' in your project which has 'connect' library in the dependency list. Actually 'connect.utils' library contains a 'merge' method that does the trick. So you can use the 3rd party implementation without adding any new 3rd party libraries.

Use merge.

$ npm install merge

Sample code:

var merge = require('merge'), // npm install -g merge
    original, cloned;

console.log(

    merge({ one: 'hello' }, { two: 'world' })

); // {"one": "hello", "two": "world"}

original = { x: { y: 1 } };

cloned = merge(true, original);

cloned.x.y++;

console.log(original.x.y, cloned.x.y); // 1, 2

If you need special behaviors like nested object extension or array replacement you can use Node.js's extendify.

var extendify = require('extendify');

_.extend = extendify({
    inPlace: false,
    arrays : 'replace',
    isDeep: true
});

obj1 = {
    a:{
        arr: [1,2]
    },
    b: 4
};

obj2 = {
    a:{
        arr: [3]
    }
};

res = _.extend(obj1,obj2);
console.log(JSON.stringify(res)); //{'a':{'arr':[3]},'b':4}

The below code will help you to merge two JSON object which has nested objects.

function mergeJSON(source1,source2){
    /*
     * Properties from the Souce1 object will be copied to Source2 Object.
     * Note: This method will return a new merged object, Source1 and Source2 original values will not be replaced.
     * */
    var mergedJSON = Object.create(source2);// Copying Source2 to a new Object

    for (var attrname in source1) {
        if(mergedJSON.hasOwnProperty(attrname)) {
          if ( source1[attrname]!=null && source1[attrname].constructor==Object ) {
              /*
               * Recursive call if the property is an object,
               * Iterate the object and set all properties of the inner object.
              */
              mergedJSON[attrname] = zrd3.utils.mergeJSON(source1[attrname], mergedJSON[attrname]);
          } 

        } else {//else copy the property from source1
            mergedJSON[attrname] = source1[attrname];

        }
      }

      return mergedJSON;
}

You can also use this lightweight npm package called absorb

It is 27 lines of code, 1kb and uses recursion to perform deep object merges.

var absorb = require('absorb');
var obj1, obj2;

obj1 = { foo: 123, bar: 456 };
obj2 = { bar: 123, key: 'value' }

absorb(obj1, obj2);

console.log(obj1); // Output: { foo: 123, bar: 123, key: 'value' }

You can also use it to make a clone or only transfer values if they don't exist in the source object, how to do this is detailed in the link provided.