带有用户输入计算的下拉列表

Question

基本上，我想通过用户输入在计算中使用下拉列表值，但是当我添加下拉值时，它要么是 NaN，要么不给出任何值。我确实尝试根据索引选择和值更改为整数进行计算，但没有奏效。任何帮助将不胜感激

<div id="stock" style="padding-top:15px">
    <label>Text Stock</label>

    <select name="textStock" id="textStock">
        <option value="None">Select Stock</option>
        <option value="50gsm">50gsm(£0.10)</option>
        <option value="120gsm">120gsm(£0.15)</option>
        <option value="150gsm">150gsm(£0.20)</option>
        <option value="200gsm">200gsm(£0.30)</option>
        <option value="250gsm">250gsm(£0.40)</option>
    </select>

</div>

注释的位是我尝试的最后一个不起作用的工作

var textStock = new Array();
textStock["None"] = 0;
textStock["50gsm"] = 0.10;
textStock["120gsm"] = 0.20;
textStock["150gsm"] = 0.30;
textStock["200gsm"] = 0.40;
textStock["250gsm"] = 0.50;

/*  var stockPrice = 0;
    var text_stock = document.getElementById(textStock).value;
    var form = document.forms["form"];
    var selected = form.elements["textStock"];
    var val = textStock[selected.value]; */


var express = document.getElementById("express");
var standard = document.getElementById("standard");
if (express.checked) {


    if (productQuantity > 50 && productQuantity < 500) {
        discountPrice = (productQuantity * basePrice) * 0.25;
        //  stockPrice = val * productQuantity;
        total = (basePrice * productQuantity) - discountPrice;
        //var totalPrice = total + stockPrice;
        alert("Express delivery applied, please expect your order within 2 working days\nTotal Price is: £" + total)

    }

Answer 1

有点不清楚您想要什么，但这应该会根据所选选项为您提供价值。

var text_stock = document.getElementById("textStock").value;
var val = textStock[text_stock]; //If "120sgm" is selected, val = 0.2