const DEBUG_all_valid = false; const DEBUG_all_stub = false; function handleRequest(request, response) { // Decode the query string to know what test we're doing. // character 1: 'I' = text/css response, 'J' = text/html response let responseCSS = (request.queryString[0] == 'I'); // character 2: redirection type - we only care about whether we're // ultimately same-origin with the requesting document ('A', 'D') or // not ('B', 'C'). let sameOrigin = (request.queryString[1] == 'A' || request.queryString[1] == 'D'); // character 3: '1' = syntactically valid, '2' = invalid, '3' = http error let malformed = (request.queryString[2] == '2'); let httpError = (request.queryString[2] == '3'); // character 4: loaded with or @import (no action required) // character 5: loading document mode: 'q' = quirks, 's' = standards let quirksMode = (request.queryString[4] == 'q'); // Our response contains a CSS rule that selects an element whose // ID is the first four characters of the query string. let selector = '#' + request.queryString.substring(0,4); // "Malformed" responses wrap the CSS rule in the construct // {} ... // This mimics what the CSS parser might see if an actual HTML // document were fed to it. Because CSS parsers recover from // errors by skipping tokens until they find something // recognizable, a style rule appearing where I wrote '...' above // will be honored! let leader = (malformed ? '{}' : ''); let trailer = (malformed ? '' : ''); // Standards mode documents will ignore the style sheet if it is being // served as text/html (regardless of its contents). Quirks mode // documents will ignore the style sheet if it is being served as // text/html _and_ it is not same-origin. Regardless, style sheets // are ignored if they come as the body of an HTTP error response. // // Style sheets that should be ignored paint the element red; those // that should be honored paint it lime. let color = ((responseCSS || (quirksMode && sameOrigin)) && !httpError ? 'lime' : 'red'); // For debugging the test itself, we have the capacity to make every style // sheet well-formed, or every style sheet do nothing. if (DEBUG_all_valid) { // In this mode, every test chip should turn blue. response.setHeader('Content-Type', 'text/css'); response.write(selector + '{background-color:blue}\n'); } else if (DEBUG_all_stub) { // In this mode, every test chip for a case where the true test // sheet would be honored, should turn red. response.setHeader('Content-Type', 'text/css'); response.write(selector + '{}\n'); } else { // Normal operation. if (httpError) response.setStatusLine(request.httpVersion, 500, "Internal Server Error"); response.setHeader('Content-Type', responseCSS ? 'text/css' : 'text/html'); response.write(leader + selector + '{background-color:' + color + '}' + trailer + '\n'); } }