title: swagger ui showing raw html code in express nodejs
body: <p>I am using swagger in nodejs express app . As expected it should have give ui in response but i am getting html code . i do not know what is wrong here.
  this is my swagger code </p>
  
  <pre><code>var swaggerUi = require('swagger-ui-express');
  // swagger definition
  var swaggerDefinition = {
    info: {
      title: 'expense manager api',
      version: '3.0.0',
      description: 'api docs for all apis',
    },
    host: 'localhost:8080',
    basePath: '/',
  };
  // options for the swagger docs
  var options = {
    // import swaggerDefinitions
    swaggerDefinition: swaggerDefinition,
    // path to the API docs
    apis: ['./server/routes/admin_routes/*.js','./server/routes/user_routes/*.js'],// pass all in array
    };
  var swaggerSpec = swaggerJSDoc(options);
  app.get('/swagger.json', function(req, res) {   res.setHeader('Content-Type', 'application/json');   res.send(swaggerSpec); });
  app.get('/api-docs',swaggerUi.serve,swaggerUi.setup(swaggerSpec));
  </code></pre>
  
  <p>but on going to localhost:8080/api-docs/ it is giving raw html code .</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html lang="en"&gt;
  &lt;head&gt;
    &lt;meta charset="UTF-8"&gt;
    &lt;title&gt;Swagger UI&lt;/title&gt;
    &lt;link rel="stylesheet" type="text/css" href="./swagger-ui.css" &gt;
    &lt;link rel="icon" type="image/png" href="./favicon-32x32.png" sizes="32x32" /&gt;&lt;link rel="icon" type="image/png" href="./favicon-16x16.png" sizes="16x16" /&gt;
  
    &lt;style&gt;
      html
      {
          box-sizing: border-box;
          overflow: -moz-scrollbars-vertical;
          overflow-y: scroll;
      }
      *,
      *:before,
      *:after
      {
          box-sizing: inherit;
      }
  
      body {
        margin:0;
        background: #fafafa;
      }
    &lt;/style&gt;
  &lt;/head&gt;
  
  &lt;body&gt;
  
  &lt;svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" style="position:absolute;width:0;height:0"&gt;
    &lt;defs&gt;
      &lt;symbol viewBox="0 0 20 20" id="unlocked"&gt;
  </code></pre>
  
  <p>i dont know what is wrong here .Any help would be great .Thanks in advance</p>