how to validate p,li,div elements text

Question

I want to validate the p,li,div element texts. examples, I have an p tag with the class name "date". then the user can insert only a date.if they inserting text I want to display alert to the user in CKEDITOR .

Is it possible to in ckeditor without using any input fields <p class="date"></p>

<p class="date">31/07/2018</p>

<p class="date">a</p> I need to display error or alert.

how can i do without onchange events. is there have any default funtionality

Answer 1

You can get elements by class in jQuery. Then the validation process is straightforward

function isDate(value) {
    var dateReg = /^\d{2}([./-])\d{2}\1\d{4}$/
    return value.match(dateReg)
}

$("p.date").map(function() {
    if(!isDate(this.innerHTML)) {
        //alert("...");
    }
});

As for the part - when to run these validation checks, you can call them on DOM updates like, insertion, deletion etc in the application layer.