Answer 1

Answer 2

Answer 3

将length设置为0可能是最好的方法，但您也可以这样做：

var mySelect = document.getElementById("select");
var len = mySelect.length;
for (var i = 0; i < len; i++) {
    mySelect.remove(0);
}

Answer 4

Answer 5

Answer 6

我能找到的最快的解决方案是以下代码（取自article）：

// Fast javascript function to clear all the options in an HTML select element
// Provide the id of the select element
// References to the old <select> object will become invalidated!
// This function returns a reference to the new select object.
function ClearOptionsFast(id)
{
    var selectObj = document.getElementById(id);
    var selectParentNode = selectObj.parentNode;
    var newSelectObj = selectObj.cloneNode(false); // Make a shallow copy
    selectParentNode.replaceChild(newSelectObj, selectObj);
    return newSelectObj;
}

Answer 7

有一种简单而优雅的方法可以做到这一点：

for(var o of document.querySelectorAll('#id > option')) {
  o.remove()
}