How to merge two arrays of JSON objects - removing duplicates and preserving order in Javascript/jQuery?

Question

jsfiddle link: http://jsfiddle.net/vN6fn/1/

Assume I have these 2 objects:

var obj1 = { data: [ 
                      {id:1, commen         


        

Answer 1

Merge two array of objects removing duplicates

• Using Es6 map() and filter() method

var obj1 = { data: [ 
                      {id:1, comment:"comment1"},
                      {id:2, comment:"comment2"},
                      {id:3, comment:"comment3"}
                   ] }

var obj2 = { data: [ 
                      {id:2, comment:"comment2"},
                      {id:3, comment:"comment3"},
                      {id:4, comment:"comment4"}
                    ]}
let obj3 = [...obj1.data, ...obj2.data]

function mergeUniqueArray(arr, comp) {

  let unique = arr
    .map(item => item[comp])

     // store the keys of the unique objects
    .map((item, i, final) => final.indexOf(item) === i && i)

    // eliminate the duplicate keys & store unique objects
    .filter(item => arr[item]).map(item => arr[item]);
    
   return unique;
}

console.log(mergeUniqueArray(obj3,'id'));