Document: DOMContentLoaded event

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The DOMContentLoaded event fires when the initial HTML document has been completely loaded and parsed, without waiting for stylesheets, images, and subframes to finish loading.

Bubbles Yes
Cancelable Yes (although specified as a simple event that isn't cancelable)
Interface Event
Event handler property None

A different event, load, should be used only to detect a fully-loaded page. It is a common mistake to use load where DOMContentLoaded would be more appropriate.

Synchronous JavaScript pauses parsing of the DOM. If you want the DOM to get parsed as fast as possible after the user has requested the page, you can make your JavaScript asynchronous and optimize loading of stylesheets. If loaded as usual, stylesheets slow down DOM parsing as they're loaded in parallel, "stealing" traffic from the main HTML document.

Examples

Basic usage

document.addEventListener('DOMContentLoaded', (event) => {
    console.log('DOM fully loaded and parsed');
});

Delaying DOMContentLoaded

<script>
  document.addEventListener('DOMContentLoaded', (event) => {
    console.log('DOM fully loaded and parsed');
  });

for( let i = 0; i < 1000000000; i++)
{} // This synchronous script is going to delay parsing of the DOM,
   // so the DOMContentLoaded event is going to launch later.
</script>

Checking whether loading is already complete

DOMContentLoaded may fire before your script has a chance to run, so it is wise to check before adding a listener.

function doSomething() {
  console.info('DOM loaded');
}

if (document.readyState === 'loading') {  // Loading hasn't finished yet
  document.addEventListener('DOMContentLoaded', doSomething);
} else {  // `DOMContentLoaded` has already fired
  doSomething();
}

Live example

HTML

<div class="controls">
  <button id="reload" type="button">Reload</button>
</div>

<div class="event-log">
  <label>Event log:</label>
  <textarea readonly class="event-log-contents" rows="8" cols="30"></textarea>
</div>

JS

const log = document.querySelector('.event-log-contents');
const reload = document.querySelector('#reload');

reload.addEventListener('click', () => {
  log.textContent ='';
  window.setTimeout(() => {
      window.location.reload(true);
  }, 200);
});

window.addEventListener('load', (event) => {
    log.textContent = log.textContent + 'load\n';
});

document.addEventListener('readystatechange', (event) => {
    log.textContent = log.textContent + `readystate: ${document.readyState}\n`;
});

document.addEventListener('DOMContentLoaded', (event) => {
    log.textContent = log.textContent + `DOMContentLoaded\n`;
});

Result

Specifications

Specification Status Comment
HTML Living Standard
The definition of 'DOMContentLoaded' in that specification.
Living Standard
HTML5
The definition of 'DOMContentLoaded' in that specification.
Recommendation

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
DOMContentLoaded eventChrome Full support 1Edge Full support YesFirefox Full support 1IE Full support 9Opera Full support 9Safari Full support 3.1WebView Android Full support YesChrome Android Full support YesFirefox Android Full support 4Opera Android Full support YesSafari iOS Full support YesSamsung Internet Android Full support Yes

Legend

Full support  
Full support

See also