title: Extract JSON from String using flutter dart
body: <p>Hello I want to extract JSON from below input string.</p>
  
  <p>I have tried bellow regex in java and it is working fine,</p>
  
  <pre><code>private static final Pattern shortcode_media = Pattern.compile("\"shortcode_media\":(\\{.+\\})");
  </code></pre>
  
  <p>I want in regex for dart.</p>
  
  <p><strong>Input String</strong></p>
  
  <pre><code>&lt;script type="text/javascript"&gt;window.__initialDataLoaded(window._sharedData);&lt;/script&gt;&lt;script type="text/javascript"&gt;window.__additionalDataLoaded('/p/B9fphP5gBeG/',{"graphql":{"shortcode_media":{"__typename":"GraphSidecar","id":"2260708142683789190","shortcode":"B9fphP5gBeG","dimensions":{"height":1326,"width":1080}}}});&lt;/script&gt;&lt;script type="text/javascript"&gt;
  &lt;script type="text/javascript"&gt;window.__initialDataLoaded(window._newData);&lt;/script&gt;&lt;script type="text/javascript"&gt;window._newData('/p/B9fphP5gBeG/',{"graphql":{"post":{"__typename":"id","id":"2260708142683789190","new_code":"B9fphP5gBeG"}}});&lt;/script&gt;&lt;script type="text/javascript"&gt;
  
  (function(){
    function normalizeError(err) {
      var errorInfo = err.error || {};
      var getConfigProp = function(propName, defaultValueIfNotTruthy) {
        var propValue = window._sharedData &amp;&amp; window._sharedData[propName];
        return propValue ? propValue : defaultValueIfNotTruthy;
      };
      return {}
    }
  )
  </code></pre>
  
  <p><strong>Expected json</strong></p>
  
  <pre><code>{"graphql":{"shortcode_media":{"__typename":"GraphSidecar","id":"2260708142683789190","shortcode":"B9fphP5gBeG","dimensions":{"height":1326,"width":1080}}}}
  </code></pre>
  
  <p><strong>Note:</strong> There are multiple json string in input string, i need json of <strong>shortcode_media</strong> tag</p>