What is the best way to ensure that JavaScript form errors disappear as soon as new input is entered?

Question

What is the best way to ensure that JavaScript form errors disappear as soon as new input is entered?

Below is the code snippet:

var nameInput = formHandle.f_Name;
var idInput = formHandle.f_Id;   

// VALIDATING NAME
        if(nameInput.value === ""){ 
                nameMsg = document.getElementById("nameErr");
                nameMsg.style.background = "red"; 
                nameMsg.innerHTML = "Please enter your name."; 
                nameMsg.style.color = "white";
                nameInput.focus();
                return false;
        }
    
        
// VALIDATING ID
        if(idInput.value === ""){
            idMsg = document.getElementById("idErr");
            idMsg.style.background = "red"; 
            idMsg.innerHTML = "Please enter the correct ID."; 
            idMsg.style.color = "white";
            idInput.focus();
            return false;
       }

The validation process begins with checking the name field. If empty, a red alert appears. However, upon entering a name and submitting again, an empty ID field triggers an error. To ensure that only the ID field displays an error when left blank, how can this be done?

View error image

javascript

Answer 1

Answer №1

Consider including an else statement for the input field like the following code snippet:

var nameInput = formHandle.f_Name;
var idInput = formHandle.f_Id;   

// NAME VALIDATION
if(nameInput.value === ""){ 
        nameMsg = document.getElementById("nameErr");
        nameMsg.style.background = "red"; 
        nameMsg.innerHTML = "Please enter your name."; 
        nameMsg.style.color = "white";
        nameInput.focus();
        return false;
} else { 
   nameMsg = document.getElementById("nameErr");
        nameMsg.style.display= "none";
}

// ID VALIDATION
if(idInput.value === ""){
    idMsg = document.getElementById("idErr");
    idMsg.style.background = "red"; 
    idMsg.innerHTML = "Please enter the correct ID."; 
    idMsg.style.color = "white";
    idInput.focus();
    return false;
}else { 
    idMsg = document.getElementById("idErr");
    idMsg.style.display= "none"; 
}

Answer 2

Consider including an else statement for the input field like the following code snippet:

var nameInput = formHandle.f_Name;
var idInput = formHandle.f_Id;   

// NAME VALIDATION
if(nameInput.value === ""){ 
        nameMsg = document.getElementById("nameErr");
        nameMsg.style.background = "red"; 
        nameMsg.innerHTML = "Please enter your name."; 
        nameMsg.style.color = "white";
        nameInput.focus();
        return false;
} else { 
   nameMsg = document.getElementById("nameErr");
        nameMsg.style.display= "none";
}

// ID VALIDATION
if(idInput.value === ""){
    idMsg = document.getElementById("idErr");
    idMsg.style.background = "red"; 
    idMsg.innerHTML = "Please enter the correct ID."; 
    idMsg.style.color = "white";
    idInput.focus();
    return false;
}else { 
    idMsg = document.getElementById("idErr");
    idMsg.style.display= "none"; 
}

Answer 3

Answer №2

To incorporate CSS classes, one method is to define a specific class using CSS:

.highlight {
  background-color: yellow;
  color: black;
}

After defining the CSS class, JavaScript can be used to toggle this class based on certain conditions:

if(inputField.value === "") { 
  errorMsg = document.getElementById("error");
  inputField.classList.add("highlight");
  errorMsg.innerHTML = "Please fill out this field."; 
  inputField.focus();
  return false;
} else {
  inputField.classList.remove("highlight");
}

Answer 4

To incorporate CSS classes, one method is to define a specific class using CSS:

.highlight {
  background-color: yellow;
  color: black;
}

After defining the CSS class, JavaScript can be used to toggle this class based on certain conditions:

if(inputField.value === "") { 
  errorMsg = document.getElementById("error");
  inputField.classList.add("highlight");
  errorMsg.innerHTML = "Please fill out this field."; 
  inputField.focus();
  return false;
} else {
  inputField.classList.remove("highlight");
}

Answer 5

Answer №3

To prevent errors from being displayed during validation, you can hide them first:

var nameInput = formHandle.f_Name;
var idInput = formHandle.f_Id;   

nameMsg = document.getElementById("nameErr");
idMsg = document.getElementById("idErr");

nameMsg.style.display = "none";
idMsg.style.display = "none";

// Ensuring Name is Valid
if(nameInput.value === ""){ 
            nameMsg.style.background = "red"; 
            nameMsg.innerHTML = "Please enter your name."; 
            nameMsg.style.color = "white";
            nameMsg.style.display = "inline-block";
            nameInput.focus();
            return false;
    }

    
// Ensuring ID is Correct
if(idInput.value === ""){
        idMsg.style.background = "red"; 
        idMsg.innerHTML = "Please enter the correct ID."; 
        idMsg.style.color = "white";
        idMsg.style.display = "inline-block";
        idInput.focus();
        return false;
    }

Answer 6

To prevent errors from being displayed during validation, you can hide them first:

var nameInput = formHandle.f_Name;
var idInput = formHandle.f_Id;   

nameMsg = document.getElementById("nameErr");
idMsg = document.getElementById("idErr");

nameMsg.style.display = "none";
idMsg.style.display = "none";

// Ensuring Name is Valid
if(nameInput.value === ""){ 
            nameMsg.style.background = "red"; 
            nameMsg.innerHTML = "Please enter your name."; 
            nameMsg.style.color = "white";
            nameMsg.style.display = "inline-block";
            nameInput.focus();
            return false;
    }

    
// Ensuring ID is Correct
if(idInput.value === ""){
        idMsg.style.background = "red"; 
        idMsg.innerHTML = "Please enter the correct ID."; 
        idMsg.style.color = "white";
        idMsg.style.display = "inline-block";
        idInput.focus();
        return false;
    }

Answer 7

Answer №4

The most convenient method currently is to leverage HTML5 input elements for handling validation automatically. In this scenario, if the values entered in the inputs are incorrect, the form will not validate and error messages will be displayed. Additionally, you can utilize the CSS pseudo-class :invalid to visually indicate any validation errors.

// To simplify form validation
const form = document.querySelector('form');
form.addEventListener('submit', handleClick, false);

function handleClick(e) {

  // Prevent form submission when it is valid,
  // and display input values in console
  e.preventDefault();
  const inputs = form.querySelectorAll('input');
  inputs.forEach(input => {
    console.log(input.value);
  });
}

input { border: 2px solid black; display: block; }
input:invalid { border: 2px solid red; }

<form>
  Number<input type="number" placeholder="A number" />
  Name<input type="text" placeholder="Letters" pattern="[A-Za-z]+" />
  Email<input type="email" placeholder="Email" />
  <button>Submit</button>
</form>

Answer 8

The most convenient method currently is to leverage HTML5 input elements for handling validation automatically. In this scenario, if the values entered in the inputs are incorrect, the form will not validate and error messages will be displayed. Additionally, you can utilize the CSS pseudo-class :invalid to visually indicate any validation errors.

// To simplify form validation
const form = document.querySelector('form');
form.addEventListener('submit', handleClick, false);

function handleClick(e) {

  // Prevent form submission when it is valid,
  // and display input values in console
  e.preventDefault();
  const inputs = form.querySelectorAll('input');
  inputs.forEach(input => {
    console.log(input.value);
  });
}

input { border: 2px solid black; display: block; }
input:invalid { border: 2px solid red; }

<form>
  Number<input type="number" placeholder="A number" />
  Name<input type="text" placeholder="Letters" pattern="[A-Za-z]+" />
  Email<input type="email" placeholder="Email" />
  <button>Submit</button>
</form>

What is the best way to ensure that JavaScript form errors disappear as soon as new input is entered?

Answer №1

Answer №2

Answer №3

Answer №4

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