JSFiddle - React, Tailwind, and code Playground

JavaScript

var oldData = [ [ "2018-04-01", 10] , [ "2018-04-02", 20] , ["2018-04-03", 30] ];
var NewData = [ [ "2018-03-30", 5], ["2018-03-31", 6], ["2018-04-01", 22] ];

function objectify(arr, arr2)
{
	 var obj = {};
    arr.forEach(function(el) { 
    	obj[el[0]] = [el[1],null]; 
    });
    arr2.forEach(function(el) { 
    	if(obj.hasOwnProperty(el[0])){
      	obj[el[0]] = [obj[el[0]][0],el[1]];
      }else{
      	obj[el[0]] = [null, el[1]];
      }
       
    });
    return obj;
}

function sortObject(o) {
    return Object.keys(o).sort().reduce((r, k) => (r[k] = o[k], r), {});
}

var newObject = sortObject(objectify(oldData, NewData));


document.write(JSON.stringify(newObject));