Javascript 如何使用用户脚本选择多个值？

我目前使用以下javascript从下面的HTML中选择一个元素。如何同时选择多个值

脚本：

//Select Forum
var forumselector = document.querySelector('select#forumchoice');
forumselector.value = 326;

HTML:

---

如果要通过同一选择框选择多个值，请尝试此操作

<select multiple="multiple">

希望这有帮助…

您可以使用document.queryselectoral并遍历节点列表：

var forumselector = document.querySelectorAll('select#forumchoice option');

for (var i = 0; i < forumselector.length; i++) {
    if (['327', '331'].indexOf(forumselector[i].value) != -1) {
        forumselector[i].setAttribute('selected', 'selected');
    }

}

document.querySelectorAll('select#selectEleId, #eleId2');

var forumselector = document.querySelectorAll('select#forumchoice option');

for (var i = 0; i < forumselector.length; i++) {
    if (['327', '331'].indexOf(forumselector[i].value) != -1) {
        forumselector[i].setAttribute('selected', 'selected');
    }

}