JSFiddle - React, Tailwind, and code Playground

JavaScript

var tab1 = [
    {"foo":"bar"}, 
    {"foo2":"bar2"}, 
    {"foo3":"bar3"} 
];

var tab2 = [ 
    {"2foo":"2bar"}, 
    {"2foo2":"2bar2"}, 
    {"2foo3":"2bar3"} ];

var tab3 = [
    {"foo":"bar"}, 
    {"foo2":"bar2"}, 
    {"foo3":"bar3"} 
];

// traditional loop
for (var i = 0; i < tab1.length; i++) {
    tab1[i] = $.extend(tab1[i], tab2[i]);
}

// jQuery version of loop
$.each(tab3, function (i, t) {
    t = $.extend(t, tab2[i]);
});

// test them both
for (var j = 0; j < tab1.length; j++) {
    console.log(tab1[j]);
    console.log(tab3[j]);        
}