问如何根据元素到给定祖先元素开头的距离来过滤元素？

EN

$(document).ready(function() {
  function thereIsImportantContent(id) {
    return $(id).find("strong").filter(function() {
      var index = $(id).text().indexOf($(this).text());
      return 0 <= index && index <= 20;
    }).length > 0;
  }

  // specs code
  describe("thereIsImportantContent", function() {

    it("accept strong near head", function() {
      expect(thereIsImportantContent($("#test_case_1")[0])).toBeTruthy();
    });

    it("accept strong near head with children", function() {
      expect(thereIsImportantContent($("#test_case_2")[0])).toBeTruthy();
    });

    it("accept wrapped strong near head", function() {
      expect(thereIsImportantContent($("#test_case_3")[0])).toBeTruthy();
    });

    it("reject strong further down", function() {
      expect(thereIsImportantContent($("#test_case_4")[0])).toBeFalsy();
    });

    it("reject strong further down with copies near head", function() {
      expect(thereIsImportantContent($("#test_case_5")[0])).toBeFalsy();
    });
  });

  // load jasmine htmlReporter
  (function() {
    var env = jasmine.getEnv();
    env.addReporter(new jasmine.HtmlReporter());
    env.execute();
  }());
});

container {
  display: none;
}

<link rel="stylesheet" href="https://cdn.jsdelivr.net/jasmine/1.3.1/jasmine.css">
<script src="https://cdn.jsdelivr.net/jasmine/1.3.1/jasmine.js"></script>
<script src="https://cdn.jsdelivr.net/jasmine/1.3.1/jasmine-html.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<container id="test_case_1">
  <!-- strong content at the beginning -> accept -->
  <p>Some <strong>content</strong></p>
  ...
  <p>other text</p>
  ...
  <p>Hey look: <strong>content</strong>!</p>
</container>

<container id="test_case_2">
  <!-- handle strong with children correctly -->
  <strong>Hey look: <span> content!</span></strong>
</container>

<container id="test_case_3">
  <p>Test</p>
  <p>Hey <strong>content!</strong></p>
</container>

<container id="test_case_4">
  <p>Something</p>
  ...
  <p>other text</p>
  ...
  <!-- strong content but located further down -> reject -->
  <p>Hey look: <strong>content</strong>!</p>
</container>

<container id="test_case_5">
  <!-- same text as in strong below triggering false accept -->
  <p>Some content</p>
  ...
  <p>other text</p>
  ...
  <!-- strong content but located further down -> should eject -->
  <p>Hey look: <strong>content</strong>!</p>
</container>

<container>
  <p>Some <strong>content</strong></p>
  ...
  <p>other text</p>
  ...
  <p>Hey look: <strong>content</strong>!</p>
</container>

container.find("strong").slice(0,10).filter(function () {
    var index = container.text().indexOf($(this).text());
    console.log("Testing: " + $(this).text(), " index: " + index);
    return 0 <= index && index <= 50
});

<container>
   <p>Some content</p>  <---position where the text "content" was found and
                             ^                             wrongly accepted       
   ...                       |Potentially important  
   <p>really long text</p>   |Element with text "content"
   ...                       |should be ignored as its far away
                             |from the start of the text
   <p>Hey look: <strong>content</strong>!</p>
</container>