如何根据另一个字段中的值将字段边框颜色更改为红色？

Question

I'm trying to compare two fields, and if the value in one field is greater than 3, I'm trying to make the other field required and have a red border to signal the user to input a value.

Here's my existing code, which I got to work to make the other field required - but I'm not sure how to add the border color in. All help is appreciated!

var v = this.getField("DISP_CODE_1").value;

if(v > 3){
event.target.required = true;
}
else {
event.target.required = false;
}

Answer 1

You can do something like this:

var v = this.getField("DISP_CODE_1").value;

if(v > 3){
    event.target.required = true;
    event.target.className += " " + classNameWithRedBorder;
}
else {
    event.target.required = false;
}

With JQuery, you could use .addClass() and .removeClass() to add/remove the css which would make it easier to act dynamically.