How To Create An Alert Message Box - W3Schools

How TO - Alerts ❮ Previous Next ❯

Learn how to create alert messages with CSS.

Alerts

Alert messages can be used to notify the user about something special: danger, success, information or warning.

× Danger! Indicates a dangerous or potentially negative action. × Success! Indicates a successful or positive action. × Info! Indicates a neutral informative change or action. × Warning! Indicates a warning that might need attention.

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Create An Alert Message

Step 1) Add HTML:

Example

<div class="alert"> <span class="closebtn" onclick="this.parentElement.style.display='none';">&times;</span> This is an alert box.</div>

If you want the ability to close the alert message, add a <span> element with an onclick attribute that says "when you click on me, hide my parent element" - which is the container <div> (class="alert").

Tip: Use the HTML entity "&times;" to create the letter "x".

Step 2) Add CSS:

Style the alert box and the close button:

Example

/* The alert message box */.alert { padding: 20px; background-color: #f44336; /* Red */ color: white; margin-bottom: 15px;} /* The close button */.closebtn { margin-left: 15px; color: white; font-weight: bold; float: right; font-size: 22px; line-height: 20px; cursor: pointer; transition: 0.3s;}/* When moving the mouse over the close button */.closebtn:hover { color: black; } Try it Yourself »

Many Alerts

If you have many alert messages on a page, you can add the following script to close different alerts without using the onclick attribute on each <span> element.

And, if you want the alerts to slowly fade out when you click on them, add opacity and transition to the alert class:

Example

<style>.alert { opacity: 1; transition: opacity 0.6s; /* 600ms to fade out */}</style><script> // Get all elements with class="closebtn"var close = document.getElementsByClassName("closebtn");var i;// Loop through all close buttonsfor (i = 0; i < close.length; i++) { // When someone clicks on a close button close[i].onclick = function(){ // Get the parent of <span class="closebtn"> (<div class="alert">) var div = this.parentElement; // Set the opacity of div to 0 (transparent) div.style.opacity = "0"; // Hide the div after 600ms (the same amount of milliseconds it takes to fade out) setTimeout(function(){ div.style.display = "none"; }, 600); }} </script> Try it Yourself »

Tip: Also check out Notes.

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