JSFiddle - React, Tailwind, and code Playground

JavaScript

var nameInfo  = [{name: "Moroni", age: 50},
                 {name: "Tiancum", age: 43},
                 {name: "Jacob", age: 27},
                 {name: "Nephi", age: 29},
                 {name: "Enos", age: 34}];

var newNameInfo  = {name: "Moroni", age: 51};
var name = newNameInfo.name;

    for (var i = 0, l = nameInfo.length; i < l; i++) {
        if (nameInfo[i].name === name) {
            nameInfo[i].age = newNameInfo.age;
            break;
        }
    }

alert(nameInfo[0].age);