如何动态获取输入值并使用javascript执行算术运算 [英] How to get an input value dynamically and perform arithmetic operations using javascript
本文介绍了如何动态获取输入值并使用javascript执行算术运算的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我创建了两个输入文本字段，用户必须给出两个值。使用JavaScript，我需要基于复选框选中这些值来执行加法，减法，乘法和除法。如何做到这一点？
I have created two input text fields by which the user have to give two values. Using javascript, I need to get those values perform addition, subtraction, multiplication and division based on the checkbox checked. How to do that?
这是我的代码..
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JS Assignment</title>
<script>
function changeCheckBox() {
try {
var max = document.myform.check.length;
var count = 0;
for (var i = 0; i < max; i++) {
if (document.myform.check[i].checked == true) {
count++;
serNoChecked = i;
}
}
if (count == 1) {
for (var i = 0; i < max; i++) {
if (document.myform.check[i].checked == false) {
document.myform.check[i].disabled = true;
}
}
} else if (count == 0) {
for (var i = 0; i < max; i++) {
document.myform.check[i].disabled = false;
}
}
if (null == max) return false;
if (count == 0) {
return true;
} else if (count > 0) {
return false;
}
} catch (e) {
alert(e.message);
}
}
</script>
<script type="text/javascript">
function arith()
{
var number1 = document.getElementById('num1').value;
var number2 = document.getElementById('num2').value;
x=num1 + num2;
var demoP=document.getElementById("demo")
demoP.innerHTML="x=" + x;
}
</script>
</head>
<body background="photo.jpg" onload="arith()">
<h3>Simple JavaScript Arithmetic Operations</h3>
<form name="myform" method="get">
Value 1 <input type ="text" id="num1"> <br><br>
Value 2 <input type="text" id="num2"> <br><br>
<input type="checkbox" name="check" value="check1" id="check1" onclick="changeCheckBox()">Addition<br>
<input type="checkbox" name="check" value="check2" id="check2" onclick="changeCheckBox()">Subtraction<br>
<input type="checkbox" name="check" value="check3" id="check3" onclick="changeCheckBox()">Multiplication<br>
<input type="checkbox" name="check" value="check4" id="check4" onclick="changeCheckBox()">Division<br><br>
<input type="submit" value="Submit">
</form>
<p id="demo"></p>
</body>
</html>
推荐答案
尝试将HTML的值发送到函数中，然后将它们用作if语句检查（或switch语句）。
Try sending the value of the HTML into the function, and then use those as an if statement check (or switch statement).
<form name="myform" method="get">
Value 1 <input type ="text" id="num1"> <br><br>
Value 2 <input type="text" id="num2"> <br><br>
<input type="checkbox" name="check" id="check1">Addition<br>
<input type="checkbox" name="check" id="check2">Subtraction<br>
<input type="checkbox" name="check" id="check3">Multiplication <br>
<input type="checkbox" name="check" id="check4">Division<br><br>
<input type="submit" value="Submit">
<p id="demo"></p>
请注意，值属性现在具有唯一值。并且你将它作为参数传递给函数。
Notice the value attributes now have unique value. And you're sending that into the function as a parameter.
现在只需要一个函数返回你想要的内容
Now just have a function that returns what you want
var newVal = "Unset";
var plus = document.getElementById("check1");
var minus = document.getElementById("check2");
var times = document.getElementById("check3");
var divide = document.getElementById("check4");
var demoP=document.getElementById("demo");
plus.onclick = function() {
var n1 = parseFloat(document.getElementById('num1').value);
var n2 = parseFloat(document.getElementById('num2').value);
newVal = n1+n2;
demoP.innerHTML="x=" + newVal;
}
minus.onclick = function() {
var n1 = parseFloat(document.getElementById('num1').value);
var n2 = parseFloat(document.getElementById('num2').value);
newVal = n1-n2;
demoP.innerHTML="x=" + newVal;
}
times.onclick = function() {
var n1 = parseFloat(document.getElementById('num1').value);
var n2 = parseFloat(document.getElementById('num2').value);
newVal = n1*n2;
demoP.innerHTML="x=" + newVal;
}
divide.onclick = function() {
var n1 = parseFloat(document.getElementById('num1').value);
var n2 = parseFloat(document.getElementById('num2').value);
newVal = n1/n2;
demoP.innerHTML="x=" + newVal;
}
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