Simple JavaScript numeric input field

Hey there, I'm a beginner learning JavaScript.

I'm currently working on creating a program that adds numbers input through text fields.

If you want to check out the HTML code, visit this link on JS Fiddle: http://jsfiddle.net/fCXMt/

My question is, how can I take user input in a text field and display the output in a P tag?

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <title>untitled</title>
</head>
<body>
<input id="value1" type="text" />
<span> + </span>
<input id="value2" type="text" />
<input type="submit" onclick="output();">
<p id="result"> </p>

<script type="text/javascript" language="javascript" charset="utf-8">
var value1 = document.getElementById('value1').innerHTML;
var value2 = document.getElementById('value2').innerHTML;

function output(){
    document.getElementById('result').innerHTML = value1 + value2;
}

</script>
</body>
</html>

Answer №1

After clicking the button, remember to extract the data from input fields and utilize the value attribute instead of innerHTML. Also, ensure that you are adding numbers together rather than concatenating strings. Here is a sample code snippet:

function calculate(){
    var num1 = document.getElementById('num1').value;
    var num2 = document.getElementById('num2').value;

    document.getElementById('result').innerHTML = parseInt(num1) + parseInt(num2);
}

Answer №2

To access the value of a textbox, use the property value instead of innerHTML. Make sure to convert the values retrieved from the textboxes using either eval or parseInt to avoid concatenating them as strings.

Ensure that your variable declarations are inside the function so that they can capture the current values of the textboxes when the function is executed.

For an updated example, check out this fiddle here.

Answer №3

To retrieve the numerical values from the input fields, you must access their "value" property and convert them to integers:

let num1 = parseInt(document.getElementById('num1').value);
let num2 = parseInt(document.getElementById('num2').value);

Answer №4

Reading the values just once is not enough; they should be read within the output function for optimal results. Additionally, it is important to parse the values as integers because using strings could lead to unexpected behavior like "1+4" being interpreted as 14. Although there may be room for improvement, this solution should suffice.

<script type="text/javascript" language="javascript" charset="utf-8>

function output(){
    var value1 = parseInt(document.getElementById('value1').value);
    var value2 = parseInt(document.getElementById('value2').value);
    document.getElementById('result').innerHTML = value1 + value2;
}

</script>

Answer №5

In terms of thoroughness: there is room for improvement in your scripting. Taking inspiration from your form, I devised a fresh jsfiddle demonstration as an alternative approach.

Answer №6

To convert a string value into a number, simply multiply it by 1.

const num1 = document.getElementById('num1').innerText * 1;
const num2 = document.getElementById('num2').innerText * 1;
document.getElementById('total').innerHTML = num1 + num2;

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