JS Validation Function with 3 arguments(//selector,message,validation function for specific input)

Question

I need to implement code which should add eventlistener and on change event check if the form is valid and add the message

let validate = function(element, info, functionValidate) {
    
    let htmlTag = document.querySelector('fieldElem');//?
    htmlTag.addEventListener('change',ev=>{
    let notif = document.createElement('span');
        document.htmlTag.appendChild(notif);//should add span element next to input

        if(fieldElem.value == '')
        {
            notif.style.visibility = "hidden"; //hide span if nothing happens
        }
        //I need to implement code which should add eventlistener and on change event check if the form is valid and add the message...

George · Accepted Answer · 2020-12-11 06:19:41Z

0

Try the following. You could also use form validation (see Form Validation Set Custom Validity for an example)

function validator(val) {
  return (val != '');
}

function validateField(element, validator, message) {

  var helper = document.createElement("span");
  var parent = element.parentElement;
  parent.appendChild(helper);
  
  
  element.addEventListener('change', function() {
    var val = element.value;
    if (!validator(val)) {
      helper.innerText = message;
    } else {
      helper.innerText = "";
    }

  });

}

validateField(document.getElementById('test'), validator, 'Wrong input');

<html>

<body>
  <form>
    <input id="test" type="text" placeholder="Type here"/>
  </form>
</body>

</html>

edited Dec 11, 2020 at 6:19

answered Dec 11, 2020 at 5:09

George

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