持有变量的 JavaScript 计算

Question

我正在使用 javascript 进行练习，我编写了这个脚本来计算 2 个变量的总和，然后在第三个方程中使用这个总和!关于如何完成这项工作的任何想法都将非常有用!

<form name="Calcultor" Method="Get" id='form1'>First Number:
    <input type="text" name="fnum" size="35" id="first">+ Second Number:
    <input type="text" name="snum" size="35" id="sec">
    <br>
    <br>Answer:
    <input type="text" name="ans" size="35" id="ans" />
    <input type="text" name="ans2" size="35" id="ans2" />
    <button type="button" onclick="Calculate();">Calculate</button>
</form>
<script lang="javascript">
    function Calculate() {
        var first = document.getElementById('first').value;
        var sec = document.getElementById('sec').value;
	var ans = document.getElementById('ans').value;

        document.getElementById('ans').value = parseInt(first) + parseInt(sec);
	document.getElementById('ans2').value = parseInt(ans);
        document.form1.submit();
    }
</script>

提前致谢!

Answer 1

这里是:

function Calculate() {
    var first = document.getElementById('first').value;
    var sec = document.getElementById('sec').value;
    var ans = document.getElementById('ans').value;

    document.getElementById('ans').value = parseInt(first) + parseInt(sec);
    document.getElementById('ans2').value = document.getElementById('ans').value;
    /*document.form1.submit();*/
}

<form name="Calcultor" Method="Get" id='form1'>First Number:
    <input type="text" name="fnum" size="35" id="first">+ Second Number:
    <input type="text" name="snum" size="35" id="sec">
    <br>
    <br>Answer:
    <input type="text" name="ans" size="35" id="ans" />
    <input type="text" name="ans2" size="35" id="ans2" />
    <button type="button" onclick="Calculate();">Calculate</button>
</form>

如果有任何不清楚的地方，请随时询问!

更新(将最后输入的值加一):

function Calculate() {
    var first = document.getElementById('first').value;
    var sec = document.getElementById('sec').value;
    var ans = document.getElementById('ans').value;

    document.getElementById('ans').value = parseInt(first) + parseInt(sec);
    document.getElementById('ans2').value = parseInt(document.getElementById('ans').value) + 1;
    /*document.form1.submit();*/
}

<form name="Calcultor" Method="Get" id='form1'>First Number:
    <input type="text" name="fnum" size="35" id="first">+ Second Number:
    <input type="text" name="snum" size="35" id="sec">
    <br>
    <br>Answer:
    <input type="text" name="ans" size="35" id="ans" />
    <input type="text" name="ans2" size="35" id="ans2" />
    <button type="button" onclick="Calculate();">Calculate</button>
</form>

您应该在对数字求和之前使用 parseInt() ，如果没有解析值，您将 string 与 number 相加，并且如预期的那样，结果将是一个多了一个字符的字符串。