revproxy-presentation/js/utils/loader.js
2020-03-07 18:48:39 +01:00

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1.1 KiB
JavaScript

/**
* Loads a JavaScript file from the given URL and executes it.
*
* @param {string} url Address of the .js file to load
* @param {function} callback Method to invoke when the script
* has loaded and executed
*/
export const loadScript = ( url, callback ) => {
const script = document.createElement( 'script' );
script.type = 'text/javascript';
script.async = false;
script.defer = false;
script.src = url;
if( typeof callback === 'function' ) {
// Success callback
script.onload = script.onreadystatechange = event => {
if( event.type === 'load' || /loaded|complete/.test( script.readyState ) ) {
// Kill event listeners
script.onload = script.onreadystatechange = script.onerror = null;
callback();
}
};
// Error callback
script.onerror = err => {
// Kill event listeners
script.onload = script.onreadystatechange = script.onerror = null;
callback( new Error( 'Failed loading script: ' + script.src + '\n' + err ) );
};
}
// Append the script at the end of <head>
const head = document.querySelector( 'head' );
head.insertBefore( script, head.lastChild );
}