如何在javascript中添加两个值 [英] How to add two values in javascript

问题描述

这是一个带有值的简单下拉列表。我试图将值拉为货币然后添加。

This is a simple dropdown with values. I'm trying to pull the values as currency then add.

未添加值（ 1 + 1 = 2 或 1 + 2 = 3 ）而是连接（ 1 + 1 = 11 或 1 + 2 = 12 ）。我在哪里错了？：

The values aren't being added (1+1=2 or 1+2=3) but instead are concatenating (1+1=11 or 1+2=12). Where am I going wrong here?:

<script>
    function displayResult()
    {
        var strm=document.getElementById("matt").options[document.getElementById("matt").selectedIndex];
        var t=strm.text.search("\\\$");
        var strb=document.getElementById("box").options[document.getElementById("box").selectedIndex];
        var b=strb.text.search("\\\$");
        var x=strm.text.substr(t+1);
        var y=strb.text.substr(b+1);
        var math= x + y;

        alert(strm.text.substr(t+1));
        alert(strb.text.substr(b+1));
        alert(math);
    }
</script>

<form>
    Select #1:
    <select id="matt">
        <option>$1.00</option>
        <option>$2.00</option>
    </select>

    <br />
    Select #2:
    <select id="box">
        <option>$3.00</option>
        <option>$4.00</option>
    </select>

</form>

<button type="button" onclick="displayResult()">Display index</button>

推荐答案

使用 parseInt（）将字符串转换为整数。

Use parseInt() to cast your strings as integers.

var math= parseInt(x,10) + parseInt(y,10);

参见 https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/parseInt

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