Change the color of the TextBox based on its value

17 Feb 20221 minute to read

You can change the color of the TextBox by validating its value using regular expression in the keyup event for predicting the numeric values as demonstrated in the following code sample.

CSHTML
Text-color.cs
<div class='wrap'>
    <label>Normal Input</label>
    <ejs-textbox id="default" placeholder="Enter numeric values" onkeyup="onKeyup(this)" ></ejs-textbox>

    <label> Floating Input </label>
    <ejs-textbox  id="float-text" placeholder="Enter numeric values" floatLabelType="Auto" onkeyup="onKeyup(this)"></ejs-textbox>

</div>

<script>
    function onKeyup(e) {
        let str = e.value.match(/^[0-9]+$/);
        if (!((str && str.length > 0)) && e.value.length) {
            e.parentElement.classList.add('e-error');
        } else {
            e.parentElement.classList.remove('e-error');
        }
    }
</script>

<style>
    .e-input-group.e-error .e-input { /* csslint allow: adjoining-classes */
        color: #f44336;
    }

    .e-float-input.e-error input { /* csslint allow: adjoining-classes */
        color: #f44336;
    }

    .wrap label { /* csslint allow: adjoining-classes */
        font-weight: bold;
    }
</style>
public ActionResult Index()
{
    return View();
}

Output be like the below.

textbox