Javascript DOM HTML Script async Property get

Introduction

Find out if a script was executed asynchronously when it was available: 

var x = document.getElementById("myScript").async

Click the button to find out if the script was executed asynchronously when it was available.

View in separate window 

<!DOCTYPE html>
<html>
<body>

<p id="p1">Hello World!</p>
<script id="myScript" src="javascript.js" async></script>

<button onclick="myFunction()">Test</button>

<p id="demo"></p>

<script>
function myFunction() {//from   ww  w  .ja v  a  2s  .  c om
  var x = document.getElementById("myScript").async;
  document.getElementById("demo").innerHTML = x;
}
</script>

</body>
</html>

The async property sets or gets whether a script should be executed asynchronously when it is available.

This property mirrors the async attribute of the <script> tag.

The async attribute is only for external scripts.

There are several ways to run an external script:

Type Meaning
async The script is executed asynchronously while the page continues the parsing
defer The script is executed when the page has finished parsing
neither async or defer The script is fetched and executed immediately, then the browser continues parsing the page

The async property accepts and returns a boolean type value.

Value Description
true The script will be executed asynchronously as soon as it is available
falseThe script will not be executed asynchronously as soon as it is available

The async property returns true if the script is executed asynchronously when it is available, otherwise it returns false.




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