Javascript向选择框添加值

var selectBox = document.getElementById("mySelect");
selectBox.innerHTML += "<option value='value1'>Option 1</option>";
selectBox.innerHTML += "<option value='value2'>Option 2</option>";

var selectBox = document.getElementById("mySelect");
var option1 = document.createElement("option");
option1.value = "value1";
option1.text = "Option 1";
selectBox.appendChild(option1);

var option2 = document.createElement("option");
option2.value = "value2";
option2.text = "Option 2";
selectBox.appendChild(option2);

var selectBox = document.getElementById("mySelect");
var option1 = new Option("Option 1", "value1");
var option2 = new Option("Option 2", "value2");
selectBox.add(option1);
selectBox.add(option2);