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function is not described

compression_test() WP 2.8.0

Test support for compressing JavaScript from PHP

Outputs JavaScript that tests if compression from PHP works as expected and sets an option with the result. Has no effect when the current user is not an administrator. To run the test again the option 'can_compress_scripts' has to be deleted.

No Hooks.

Return

Nothing (null).

Usage

compression_test();

Code of compression test: wp-admin/includes/template.php VER 5.1.1

<?php
function compression_test() {
	?>
	<script type="text/javascript">
	var compressionNonce = <?php echo wp_json_encode( wp_create_nonce( 'update_can_compress_scripts' ) ); ?>;
	var testCompression = {
		get : function(test) {
			var x;
			if ( window.XMLHttpRequest ) {
				x = new XMLHttpRequest();
			} else {
				try{x=new ActiveXObject('Msxml2.XMLHTTP');}catch(e){try{x=new ActiveXObject('Microsoft.XMLHTTP');}catch(e){};}
			}

			if (x) {
				x.onreadystatechange = function() {
					var r, h;
					if ( x.readyState == 4 ) {
						r = x.responseText.substr(0, 18);
						h = x.getResponseHeader('Content-Encoding');
						testCompression.check(r, h, test);
					}
				};

				x.open('GET', ajaxurl + '?action=wp-compression-test&test='+test+'&_ajax_nonce='+compressionNonce+'&'+(new Date()).getTime(), true);
				x.send('');
			}
		},

		check : function(r, h, test) {
			if ( ! r && ! test )
				this.get(1);

			if ( 1 == test ) {
				if ( h && ( h.match(/deflate/i) || h.match(/gzip/i) ) )
					this.get('no');
				else
					this.get(2);

				return;
			}

			if ( 2 == test ) {
				if ( '"wpCompressionTest' == r )
					this.get('yes');
				else
					this.get('no');
			}
		}
	};
	testCompression.check();
	</script>
	<?php
}