object_creator.js

let my_object = [
    {
        value: "",
        class: "A"
    },
    {
        value: "",
        class: "B"
    },
    {
        value: "",
        class: "C"
    }
];

let myArray = ["value1", "value2", "value3"];

my_object.map((item, index) => {
    item.value = myArray[index]; // assign item.value by current index
});

console.log(JSON.stringify(my_object)); 
//[{"value":"value1","class":"A"},{"value":"value2","class":"B"},{"value":"value3","class":"C"}]