Adding two numbers concatenates them instead of ca

I am adding two numbers, I get a correct value.

Got the value after sum

function myFunction() {
  var y = document.getElementById("txt1").value;
  var z = document.getElementById("txt2").value;
  var x = Number(y) + Number(z);
  document.getElementById("demo").innerHTML = x;
}

<p>
  Click the button to calculate x.
  <button onclick="myFunction()">Try it</button>
</p>
<p>
  Enter first number:
  <input type="text" id="txt1" name="text1" value="1">
  Enter second number:
  <input type="text" id="txt2" name="text2" value="2">
</p>
<p id="demo"></p>

标签： javascript html

20条回答

浅入江南

2楼-- · 2018-12-31 06:17

  <input type="text" name="num1" id="num1" onkeyup="sum()">
  <input type="text" name="num2" id="num2" onkeyup="sum()">
  <input type="text" name="num2" id="result">

  <script>
     function sum()
     {

        var number1 = document.getElementById('num1').value;
        var number2 = document.getElementById('num2').value;

        if (number1 == '') {
           number1 = 0
           var num3 = parseInt(number1) + parseInt(number2);
           document.getElementById('result').value = num3;
        }
        else if(number2 == '')
        {
           number2 = 0;
           var num3 = parseInt(number1) + parseInt(number2);
           document.getElementById('result').value = num3;
        }
        else
        {
           var num3 = parseInt(number1) + parseInt(number2);
           document.getElementById('result').value = num3;
        }

     }
  </script>

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姐姐魅力值爆表

3楼-- · 2018-12-31 06:18

I just use Number():

var i=2;  
var j=3;  
var k = Number(i) + Number(j); // 5

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孤独总比滥情好

4楼-- · 2018-12-31 06:20

You are missing the type conversion during the addition step...
var x = y + z; should be var x = parseInt(y) + parseInt(z);

 <!DOCTYPE html>

 <html>
 <body>
  <p>Click the button to calculate x.</p>
  <button onclick="myFunction()">Try it</button>
  <br/>
  <br/>Enter first number:
  <input type="text" id="txt1" name="text1">Enter second number:
  <input type="text" id="txt2" name="text2">
  <p id="demo"></p>
 <script>
    function myFunction() 
    {
      var y = document.getElementById("txt1").value;
      var z = document.getElementById("txt2").value;
      var x = parseInt(y) + parseInt(z);
      document.getElementById("demo").innerHTML = x;
    }
 </script>
 </body>
 </html>

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琉璃瓶的回忆

5楼-- · 2018-12-31 06:20

if we have two input fields then get the values from input fields then add them using javascript.

$('input[name="yourname"]').keyup(function(event) {
    /* Act on the event */ 
    var value1 = $(this).val();     
    var value2 = $('input[name="secondName"]').val();
    var roundofa = +value2+ +value1;

    $('input[name="total"]').val(addition);             
});

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后来的你喜欢了谁

6楼-- · 2018-12-31 06:21

Here goes your Code by parsing the variables in the function.

    <html>
      <body>
        <p>Click the button to calculate x.</p>
        <button onclick="myFunction()">Try it</button>
        <br/>
        <br/>Enter first number:
        <input type="text" id="txt1" name="text1">
        <br>Enter second number:
        <input type="text" id="txt2" name="text2">
        <p id="demo"></p>
        <script>
          function myFunction() {
            var y = parseInt(document.getElementById("txt1").value);
            var z = parseInt(document.getElementById("txt2").value);
            var x = y + z;
            document.getElementById("demo").innerHTML = x;
          }
        </script>
      </body>
    </html>

Answer

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怪性笑人.

7楼-- · 2018-12-31 06:22

Use parseInt(...) but make sure you specify a radix value; otherwise you will run into several bugs (if the string begins with "0", the radix is octal/8 etc.).

var x = parseInt(stringValueX, 10);
var y = parseInt(stringValueY, 10);

alert(x + y);

Hope this helps!

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Adding two numbers concatenates them instead of ca

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