从html5 asp.net中的另一个文本框中设置一个文本框的值

Question

I have 3 text boxes in my mvc4 asp.net View.

Code is:-

<table>
<tr><td>A:</td><td>@Html.TextBox("A")</td></tr>
<tr><td>B:</td><td>@Html.TextBox("B")</td></tr>
<tr><td>Answer:</td><td>@Html.TextBox("C")</td></tr>
</table>

For Example,What i want is,

As soon as i enter "3" in TextBox A and "2" in TextBox B, the answer "5" should be displayed instantly in TextBox C, without me hitting any submit button.

How can i do this?

Thank You.

Answer 1

You need to use some form of Javascript to do this. Here is a piece of vanilla JavaScript which adds an event handler onto both A and B, which compares the value of the textboxes and displays the required value in C if the condition is met:

// Get all the textboxes by their IDs
var textboxA = document.getElementById("A");
var textboxB = document.getElementById("B");
var textboxC = document.getElementById("C");
// Add a handler for the keyup event
textboxA.addEventListener("keyup", showAnswer, false);
textboxB.addEventListener("keyup", showAnswer, false);

function showAnswer() {
    // Convert the values from a string to a float
    var valA = parseFloat(textboxA.value);
    var valB = parseFloat(textboxB.value);
    // Make sure both values are valid numbers
    if(!isNaN(valA) && !isNaN(valB)) {
        // Show the calculated value in the C box
        textboxC.value = valA + valB;
    }
    else {
        // Can't do any calculations, just show a blank value
        textboxC.value = "";
    }
}

Here is a fiddle to demonstrate.

There are easier ways of doing this with jQuery:

$(function() {
    $("#A, #B").on("keyup blur", function() {
        var valA = parseFloat($("#A").val());
        var valB = parseFloat($("#B").val());
        if(!isNaN(valA) && !isNan(valB)) {
            $("#C").val(valA + valB);
        }
        else {
            $("#C").val("");
        }
    });
});

Answer 2

Here another solution using JQuery

SAMPLE DEMO

For using JQuery you need to add JQuery lib in your head tag , just copy paste the below line in head tag.

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>

JQuery:

<script type="text/javascript" >

$(document).ready(function (){

    $("#Txt_1").on('input', function () {
        sumCal();
    });

    $("#Txt_2").on('input', function () {
        sumCal();
    });

    function sumCal() {

        var txt1 = $("#Txt_1").val();
        var txt2 = $("#Txt_2").val();
        var result = Number(txt1) + Number(txt2);
        $("#Txt_3").val(result);
    }
});
</script>

Answer 3

Try this

$(document).ready(function(){

  $("#txtbox2").keyup(function(){
    var txt01= parseInt ($("#txtbox1").val(),10);

 var txt02= parseInt( $("#txtbox2").val(),10);

$("#txtbox3").val( txt01+txt02);

  });
});