如何使用 array.push 为数组添加值？

Question

I would like to add a value with array.push to my first element of array [0] to the field yesterday, I don't know very well what the structure is to be able to add this value. try the following way

var cumpleaños = [
  {
    ayer: "",
  },
  {
    hoy: "12-07-20",
}  ,
  {
    mañana: "12-08-20"
}
];
cumpleaños.push([0].ayer.("12-06-20"))
console.log(cumpleaños[0].ayer)

Thank you very much for the help!

Answer 1

You don't need to push anything since you're not adding a new value, you're just modifying an existing value:

cumpleaños[0].ayer = "12-06-20";

As a side note, your data structure would be much more effectively represented by a single object not inside an array:

const cumpleaños = {
    ayer: "12-06-20",
    hoy: "12-07-20",
    mañana: "12-08-20"
};

Answer 2

You would do assignment to the first element of the array. (If the oder is always the same)

cumpleaños[0].ayer = "12-06-20"