javascript - jQuery : Sum multiple select value if only selected

Question

如果仅选择该项目，如何对所选多个项目的值求和。从示例中我想获取“X12SO+X13SO=30”的值

let sum = 0;
$("select[name='myselect[]'] option").each(function(){
  sum += +this.value.split("|")[1];
});
$("input[name='myresult']").val(sum);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

 <select multiple class="form-control" id="multipleSelect" name="myselect[]">
<option value="X12SO|10">X12SO</option>
<option value="X13SO|20">X13SO</option>
<option value="X14SO|30">X14SO</option>
<option value="X15SO|40">X15SO</option>
<option value="X16SO|50">X16SO</option>
</select>

<input type="text" name="myresult">

Answer 1

使用onchange来检测所选选项是否发生更改。

let sum = 0;
$("#multipleSelect").on("change", function(){
  sum = 0;
  // if there are no options being selected, it would be an empty array[]
  // and sum each splited value
  ($(this).val() || []).map(v=>sum += +v.split("|")[1])
  $("input").val(sum);
})

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

 <select multiple class="form-control" id="multipleSelect" name="myselect[]">
<option value="X12SO|10">X12SO</option>
<option value="X13SO|20">X13SO</option>
<option value="X14SO|30">X14SO</option>
<option value="X15SO|40">X15SO</option>
<option value="X16SO|50">X16SO</option>
</select>

<input type="text" name="myresult">