Myujth

I want to replace / add new values in an immutable list like:

const old = [
 id: 1, value: 'foo' ,
 id: 3, value: 'bar' ,
 id: 2, value: 'baz' ,
]

const new = [
 id: 1, value: 'quux' , // update
 id: 4, value: 'asd' , // push

]

union == [
 id: 1, value: 'quux' , // updated 
 id: 3, value: 'bar' ,
 id: 2, value: 'baz' ,
 id: 4, value: 'asd' , // new
]

I can use any data type if lists don't have this functionality but something has

If this isn't built in immutable.js just say that, i already wrote a script for this, i'm just missing the built in method

Algorithms for union

First you have to maintain two map with key as id and value as object then check for length of array which is of bigger size and pass the bigger size array with small size map to merged function there you can iterate over the array and check if it's exists in the map if yes then update the object and delete that row from map otherwise add the object into output. After the for loop complete check if map has element present then push all the values from map into output array and return;

index.js

const old = [
 id: 1, value: 'foo' ,
 id: 3, value: 'bar' ,
 id: 2, value: 'baz' ,
];

const newa = [
 id: 1, value: 'quux' , // update
 id: 4, value: 'asd' , // push

];

 function merged(input,filterMap)
 var output = ;
 input.forEach(function(eachRow)
 if(filterMap.hasOwnProperty(eachRow.id))
 output.push(Object.assign(eachRow,filterMap[eachRow.id]));
 delete filterMap[eachRow.id];
 else
 output.push(eachRow);
 
 );

 if(Object.keys(filterMap).length > 0)
 output = output.concat(Object.values(filterMap));
 
 return output;
 

function parseData(first,second)
 var mapFirst = ,
 mapSecond = ;
 var output = ;
 first.forEach(function(eachRow)
 mapFirst[eachRow.id] = eachRow;
 );

 second.forEach(function(eachRow)
 mapSecond[eachRow.id] = eachRow;
 );

 if(first.length > second.length)
 return merged(first,mapSecond);
 else
 return merged(second,mapFirst);
 


console.log(parseData(old,newa));

Working jsFiddle demo - https://jsfiddle.net/qz25hnmf/