To populate drop down list with array with JavaScript, we call the createElement method.

For instance, we write

const arr = ["1", "2", "3", "4"];
arr.forEach((item) => {
  const optionObj = document.createElement("option");
  optionObj.textContent = item;
  document.getElementById("myselect").appendChild(optionObj);
});

to call arr.forEach with a callback that calls createElement to create an option element.

Then we set the text of the option by setting the textContent property.

Then we select the select element and append the option element to it with appendChild.