JSFiddle - React, Tailwind, and code Playground

JavaScript

function merge_options(obj1,obj2){
    var obj3 = {};
    for (var attrname in obj1) { obj3[attrname] = obj1[attrname]; }
    for (var attrname in obj2) { obj3[attrname] = obj2[attrname]; }
    return obj3;
}
var obj = {
a: '1',
b: '2'
}

var obj2 = {
c: '3',
d: '4'
}
alert(merge_options(obj,obj2)["a"]);
alert(merge_options(obj,obj2)["b"]);
alert(merge_options(obj,obj2)["c"]);
alert(merge_options(obj,obj2)["d"]);