JSFiddle - React, Tailwind, and code Playground

by radu

JavaScript

var arr1 = [['Albania','1000'],['United Kingdom','1000']],
    arr2 = [['Albania','1000'],['UK','1000']],
    sum = [],
    index = -1;

var mergedArray = arr1.concat(arr2);

for (var i = 0, n = mergedArray.length; i !== n; i++) {

    for (var j = 0, m = sum.length; j !== m; j++) {   
        if (sum[j].indexOf(mergedArray[i][0]) !== -1) {
            index = j;
            break;            
        } else {
            index = -1;
        }
    }

    if (index !== -1) {
        sum[index][1] = (
            parseInt(sum[index][1], 10) +  
            parseInt(mergedArray[i][1], 10)
        ).toString();
    } else {
        sum.push([mergedArray[i][0], mergedArray[i][1]]);
    }
}