Nowing the number of an array

Question

How can I know in which position "Januar" in the array is (in a number)?^ In the end, I want to get 0 for "January" and 1 for "February" .

var Monat = ["January", "February"]

Answer 1

The indexOf() method returns the first index at which a given element can be found in the array, or -1 if it is not present.

So in your case

 Monat.indexOf("January")

Should return 0

Answer 2

You could use findIndex of Array.prototype to find the index.

var Monat = ["January", "February"];
function findIndex(day) {
  return Monat.findIndex((x) => x === day);
}

const index = findIndex("January");
console.log(index);
const index2 = findIndex("February");
console.log(index2);

Answer 3

You can use indexOf for this. it will return the index of the first matched item in the array if found or -1 otherwise.

var Monat = ["January", "February"];

console.log(Monat.indexOf("January")); //0

console.log(Monat.indexOf("February")); //1

console.log(Monat.indexOf("not exists")); //-1