doc: improved example for http.get

PR-URL: https://github.com/nodejs/node/pull/9065
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

doc/api/http.md

@@ -1448,16 +1448,47 @@ added: v0.3.6
 * Returns: {http.ClientRequest}
 
 Since most requests are GET requests without bodies, Node.js provides this
-convenience method. The only difference between this method and [`http.request()`][]
-is that it sets the method to GET and calls `req.end()` automatically.
+convenience method. The only difference between this method and
+[`http.request()`][] is that it sets the method to GET and calls `req.end()`
+automatically. Note that response data must be consumed in the callback
+for reasons stated in [`http.ClientRequest`][] section.
 
-Example:
+The `callback` is invoked with a single argument that is an instance of
+[`http.IncomingMessage`][]
+
+JSON Fetching Example:
 
 ```js
-http.get('http://www.google.com/index.html', (res) => {
-  console.log(`Got response: ${res.statusCode}`);
-  // consume response body
-  res.resume();
+http.get('http://nodejs.org/dist/index.json', (res) => {
+  const statusCode = res.statusCode;
+  const contentType = res.headers['content-type'];
+
+  let error;
+  if (statusCode !== 200) {
+    error = new Error(`Request Failed.\n` +
+                      `Status Code: ${statusCode}`);
+  } else if (!/^application\/json/.test(contentType)) {
+    error = new Error(`Invalid content-type.\n` +
+                      `Expected application/json but received ${contentType}`);
+  }
+  if (error) {
+    console.log(error.message);
+    // consume response data to free up memory
+    res.resume();
+    return;
+  }
+
+  res.setEncoding('utf8');
+  let rawData = '';
+  res.on('data', (chunk) => rawData += chunk);
+  res.on('end', () => {
+    try {
+      let parsedData = JSON.parse(rawData);
+      console.log(parsedData);
+    } catch (e) {
+      console.log(e.message);
+    }
+  });
 }).on('error', (e) => {
   console.log(`Got error: ${e.message}`);
 });