JSON improvements: throw if JSON parsing failed; number, boolean can be passed directly as payload for encoding to JSON #2613, #61, #907 (#3688)

* Draft

* Added support for primitive types to be converted to JSON if the request Content-Type is 'application/json';
Added throwing SyntaxError if JSON parsing failed and responseType is json;
Added transitional option object;
Added options validator to assert transitional options;
Added transitional option `silentJSONParsing= true` for backward compatibility;
Updated README.md;
Updated typings;

* Fixed isOlderVersion helper;
Fixed typo;
Added validator.spec.js;

* Added forcedJSONParsing transitional option #2791

* `transformData` is now called in the default configuration context if the function context is not specified (for tests compatibility);

* Added `transitional.clarifyTimeoutError` to throw ETIMEDOUT error instead of generic ECONNABORTED on request timeouts;
Added support of onloadend handler if available instead of onreadystatechange;
Added xhr timeout test;
Fixed potential bug of xhr adapter with proper handling timeouts&errors (FakeXMLHTTPRequest failed to handle timeouts);

lib/adapters/http.js

@@ -284,7 +284,12 @@ module.exports = function httpAdapter(config) {
       // ClientRequest.setTimeout will be fired on the specify milliseconds, and can make sure that abort() will be fired after connect.
       req.setTimeout(config.timeout, function handleRequestTimeout() {
         req.abort();
-        reject(createError('timeout of ' + config.timeout + 'ms exceeded', config, 'ECONNABORTED', req));
+        reject(createError(
+          'timeout of ' + config.timeout + 'ms exceeded',
+          config,
+          config.transitional && config.transitional.clarifyTimeoutError ? 'ETIMEDOUT' : 'ECONNABORTED',
+          req
+        ));
       });
     }
 

lib/adapters/xhr.js

@@ -13,6 +13,7 @@ module.exports = function xhrAdapter(config) {
   return new Promise(function dispatchXhrRequest(resolve, reject) {
     var requestData = config.data;
     var requestHeaders = config.headers;
+    var responseType = config.responseType;
 
     if (utils.isFormData(requestData)) {
       delete requestHeaders['Content-Type']; // Let the browser set it
@@ -33,23 +34,14 @@ module.exports = function xhrAdapter(config) {
     // Set the request timeout in MS
     request.timeout = config.timeout;
 
-    // Listen for ready state
-    request.onreadystatechange = function handleLoad() {
-      if (!request || request.readyState !== 4) {
+    function onloadend() {
+      if (!request) {
         return;
       }
-
-      // The request errored out and we didn't get a response, this will be
-      // handled by onerror instead
-      // With one exception: request that using file: protocol, most browsers
-      // will return status as 0 even though it's a successful request
-      if (request.status === 0 && !(request.responseURL && request.responseURL.indexOf('file:') === 0)) {
-        return;
-      }
-
       // Prepare the response
       var responseHeaders = 'getAllResponseHeaders' in request ? parseHeaders(request.getAllResponseHeaders()) : null;
-      var responseData = !config.responseType || config.responseType === 'text' ? request.responseText : request.response;
+      var responseData = !responseType || responseType === 'text' ||  responseType === 'json' ?
+        request.responseText : request.response;
       var response = {
         data: responseData,
         status: request.status,
@@ -63,7 +55,30 @@ module.exports = function xhrAdapter(config) {
 
       // Clean up request
       request = null;
-    };
+    }
+
+    if ('onloadend' in request) {
+      // Use onloadend if available
+      request.onloadend = onloadend;
+    } else {
+      // Listen for ready state to emulate onloadend
+      request.onreadystatechange = function handleLoad() {
+        if (!request || request.readyState !== 4) {
+          return;
+        }
+
+        // The request errored out and we didn't get a response, this will be
+        // handled by onerror instead
+        // With one exception: request that using file: protocol, most browsers
+        // will return status as 0 even though it's a successful request
+        if (request.status === 0 && !(request.responseURL && request.responseURL.indexOf('file:') === 0)) {
+          return;
+        }
+        // readystate handler is calling before onerror or ontimeout handlers,
+        // so we should call onloadend on the next 'tick'
+        setTimeout(onloadend);
+      };
+    }
 
     // Handle browser request cancellation (as opposed to a manual cancellation)
     request.onabort = function handleAbort() {
@@ -93,7 +108,10 @@ module.exports = function xhrAdapter(config) {
       if (config.timeoutErrorMessage) {
         timeoutErrorMessage = config.timeoutErrorMessage;
       }
-      reject(createError(timeoutErrorMessage, config, 'ECONNABORTED',
+      reject(createError(
+        timeoutErrorMessage,
+        config,
+        config.transitional && config.transitional.clarifyTimeoutError ? 'ETIMEDOUT' : 'ECONNABORTED',
         request));
 
       // Clean up request
@@ -133,16 +151,8 @@ module.exports = function xhrAdapter(config) {
     }
 
     // Add responseType to request if needed
-    if (config.responseType) {
-      try {
-        request.responseType = config.responseType;
-      } catch (e) {
-        // Expected DOMException thrown by browsers not compatible XMLHttpRequest Level 2.
-        // But, this can be suppressed for 'json' type as it can be parsed by default 'transformResponse' function.
-        if (config.responseType !== 'json') {
-          throw e;
-        }
-      }
+    if (responseType && responseType !== 'json') {
+      request.responseType = config.responseType;
     }
 
     // Handle progress if needed