title: get last element id number in JQuery and plus one
body: <p>how can i get the last id number of below code dynamically? (in this code = obj_9)</p>
  
  <pre><code>            &lt;div id="objects"&gt;
              &lt;div class="obj_item"&gt;&lt;img id="obj_1" class="ui-widget-content" src="elements/abstract_celtic_knot_in_blue_tattoo_design.png" /&gt;&lt;/div&gt;
              &lt;div class="obj_item"&gt;&lt;img id="obj_2" class="ui-widget-content" src="elements/anchor_tears_the_skin_tatoo_design.png" /&gt;&lt;/div&gt;
              &lt;div class="obj_item"&gt;&lt;img id="obj_3" class="ui-widget-content" src="elements/armband_tattoo_with_cross_in_the_center_idea.png" /&gt;&lt;/div&gt;
              &lt;div class="obj_item"&gt;&lt;img id="obj_4" class="ui-widget-content" src="elements/armband_tribal_sign_tattoo_design.png" /&gt;&lt;/div&gt;
              &lt;div class="obj_item"&gt;&lt;img id="obj_5" class="ui-widget-content" src="elements/bat_covered_by_the_wings_tattoo_design.png" /&gt;&lt;/div&gt;
              &lt;div class="obj_item"&gt;&lt;img id="obj_6" class="ui-widget-content" src="elements/black_eye_tattoo_idea.png" /&gt;&lt;/div&gt;
              &lt;div class="obj_item"&gt;&lt;img id="obj_7" class="ui-widget-content" src="elements/black_sketch_of_native_indian_chief_tattoo_design.png" /&gt;&lt;/div&gt;
              &lt;div class="obj_item"&gt;&lt;img id="obj_8" class="ui-widget-content" src="elements/clown_with_two_knives_tattoo_idea.png" /&gt;&lt;/div&gt;
              &lt;div class="obj_item"&gt;&lt;img id="obj_9" class="ui-widget-content" src="elements/eagle_is_catching_prey_tattoo_design.png" /&gt;&lt;/div&gt;
              &lt;/div&gt;
  </code></pre>
  
  <p>and finally convert id to int number and plus it one.</p>
  
  <p>thank you</p>