javascript - 我想显示两个数字的加法而不使用任何按钮

This question already has answers here:

Adding two numbers concatenates them instead of calculating the sum
（20个答案）
去年关门了。
我有两个idno1和no2的输入框。我必须在两个输入端加上两个整数值，并且不使用任何按钮来显示它们的和。我的代码可以工作，但它只显示单个值，而不是计算的和。
当用户只是输入时，如何实时显示我的附加值？

var c;
var a = document.getElementById("no1");
var b = document.getElementById("no2");
var number = document.getElementById("number");
var m = document.getElementById("message");

a.onfocus = function() {
  m.style.display = "block";
}

a.onblur = function() {
  m.style.display = "none";
}

a.onkeyup = function() {
  var c;
  if (isNaN(a.value) == false) {
    c = a.value + b.value;
    m.innerHTML = c;
  } else {

    m.innerHTML = "<font color='red' size='45px'><strong>Must containe number only</strong></font>";
  }
}
b.onfocus = function() {
  m.style.display = "block";
}
b.onblur = function() {
  m.style.display = "none";
}
b.onkeyup = function() {

  if (isNaN(b.value) == false) {
    c = a.value + b.value;
    m.innerHTML = c;
  } else {

    m.innerHTML = "<font color='red' size='45px'><strong>Must containe number only</strong></font>";
  }
}

<div class="container">
  <input type="text" id="no1" name="no1" />
  <input type="text" id="no2" name="no2" />
  <button onclick="myFun()">Press Me</button>
</div>

<center>
  <font color="blue" size="45px" id="message"></font>
</center>

最佳答案

var c;
var a = document.getElementById("no1");
var b = document.getElementById("no2");
var number = document.getElementById("number");
var m = document.getElementById("message");
a.onfocus = function() {
m.style.display = "block"; }
a.onblur = function() {
m.style.display = "none"; }
a.onkeyup = function() {
var c;
if (isNaN(a.value) == false) {
c = Number(a.value) + Number(b.value);
m.innerHTML = c;
}
else {
m.innerHTML = "<font color='red' size='45px'><strong>Must containe number only</strong></font>";
}
}
b.onfocus = function() {
m.style.display = "block"; }
b.onblur = function() {
m.style.display = "none"; }
b.onkeyup = function() {

if (isNaN(b.value) == false) {
c = Number(a.value) + Number(b.value);
m.innerHTML = c;
}
else {
m.innerHTML = "<font color='red' size='45px'><strong>Must containe number only</strong></font>";
}
}

关于javascript - 我想显示两个数字的加法而不使用任何按钮，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/49412586/