I have a form with one textbox. I want to check when the textbox value is empty and make some sort of red border surrounding the textbox itself when it's empty.

if (document.getElementById('pageh').value == "") {
    alert("One of the fields is empty.");
    return false;
}

That's my validation, but how do I add the red border?

I have a form with one textbox. I want to check when the textbox value is empty and make some sort of red border surrounding the textbox itself when it's empty.

if (document.getElementById('pageh').value == "") {
    alert("One of the fields is empty.");
    return false;
}

That's my validation, but how do I add the red border?

• javascript
• html

2 Answers 2

var field = document.getElementById('pageh');

if (field.value == "") {
    document.getElementById('pageh').style.border = "solid 1px red";
    alert("One of the fields is empty.");
    return false;
}

Maybe something like that?

var textbox = document.getElementById("pageh");
if (textbox.value.replace(/^\s+|\s+$/g, "") === "") {
    textbox.style.border = "1px solid #ff0000";
}

Note, don't be afraid of replace part: this is just cross-browser text trim.