Function loadExternalMarkdown

plugin/markdown/plugin.js:263–305

( section )

	}

	function loadExternalMarkdown( section ) {

		return new Promise( function( resolve, reject ) {

			const xhr = new XMLHttpRequest(),
				url = section.getAttribute( 'data-markdown' );

			const datacharset = section.getAttribute( 'data-charset' );

			// see https://developer.mozilla.org/en-US/docs/Web/API/element.getAttribute#Notes
			if( datacharset !== null && datacharset !== '' ) {
				xhr.overrideMimeType( 'text/html; charset=' + datacharset );
			}

			xhr.onreadystatechange = function( section, xhr ) {
				if( xhr.readyState === 4 ) {
					// file protocol yields status code 0 (useful for local debug, mobile applications etc.)
					if ( ( xhr.status >= 200 && xhr.status < 300 ) || xhr.status === 0 ) {

						resolve( xhr, url );

					}
					else {

						reject( xhr, url );

					}
				}
			}.bind( this, section, xhr );

			xhr.open( 'GET', url, true );

			try {
				xhr.send();
			}
			catch ( e ) {
				console.warn( 'Failed to get the Markdown file ' + url + '. Make sure that the presentation and the file are served by a HTTP server and the file can be found there. ' + e );
				resolve( xhr, url );
			}

		} );

	}

	/**
	 * Check if a node value has the attributes pattern.