Ashley P.

asked • 11/21/19

Simple Adder HTML JavaScript

Create the form structure shown in Figure 2, below. Write a JavaScript function according to the following requirements.

 A user should be allowed to enter two numbers in text boxes.

 When a user click on “+” button;

o Check whether inputs in the text boxes are numbers (use isNAN). If not, meaningful message should be displayed considering wrong inputs.

o If the inputs are numbers, summation of two numbers should be displayed on 3rd box (total)

I wrote the following code but the total appears and does not remain in the text box and disappears

<script type="text/javascript">

function myfunction() {

var first = document.getElementById("textbox1").value;

var second = document.getElementById("textbox2").value;

alert( first );

if(isNaN(first) && isNaN(second))


alert( "Not a number" );

return false;




var answer =parseFloat(first)+parseFloat(second);

var textbox3 = document.getElementById('textbox3');






1<sup>st</sup> Number <input type="text" name="textbox1" id="textbox1" />


2<sup>nd</sup> Number <input type="text" name="textbox2" id="textbox2" />

</br> <br>

<input type="submit" name="button" id="button1" onclick="myfunction()" value="+" />



<input type="text" name="textbox3" id="textbox3" readonly="true"/>



1 Expert Answer


Patrick B. answered • 11/24/19

Math and computer tutor/teacher

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