Select and Focus a Checkbox Input using Javascript

I have a checkbox that is used to filter out search results depending on state. Additionally, a user can select district too to filter out results. In case a person selects a particular district instead of state, i want to automatically select the right state for that district using JavaScript and be able to focus. How can i use JavaScript code to select any checkbox and focus on it using JavaScript? Any assistance is much appreciated.

JSFiddle

<li class="cp_state">
    <label class="title">State</label>
    <div class="handle close dashicons-before"></div>
        <div class="element">   
        <div class="scrollbox">
        <ol class="checkboxes">
            <li><input id="testing" type="checkbox" name="cp_state[]" value="Johor"  />&nbsp;<label for="cp_state[]">Johor</label></li>
            <li><input type="checkbox" name="cp_state[]" value="Kedah"  />&nbsp;<label for="cp_state[]">Kedah</label></li>
            <li><input type="checkbox" name="cp_state[]" value="Kelantan"  />&nbsp;<label for="cp_state[]">Kelantan</label></li>
            <li><input type="checkbox" name="cp_state[]" value="Wilayah Persekutuan Kuala Lumpur"  />&nbsp;<label for="cp_state[]">Wilayah Persekutuan Kuala Lumpur</label></li>
            <li><input type="checkbox" name="cp_state[]" value="Wilayah Persekutuan Labuan"  />&nbsp;<label for="cp_state[]">Wilayah Persekutuan Labuan</label></li>
            <li><input type="checkbox" name="cp_state[]" value="Melaka"  />&nbsp;<label for="cp_state[]">Melaka</label></li>
            <li><input type="checkbox" name="cp_state[]" value="Negeri Sembilan"  />&nbsp;<label for="cp_state[]">Negeri Sembilan</label></li>
            <li><input type="checkbox" name="cp_state[]" value="Pahang"  />&nbsp;<label for="cp_state[]">Pahang</label></li>
            <li><input type="checkbox" name="cp_state[]" value="Wilayah Persekutuan Putra Jaya"  />&nbsp;<label for="cp_state[]">Wilayah Persekutuan Putra Jaya</label></li>
            <li><input type="checkbox" name="cp_state[]" value="Perlis"  />&nbsp;<label for="cp_state[]">Perlis</label></li>
            <li><input type="checkbox" name="cp_state[]" value="Pulau Pinang"  />&nbsp;<label for="cp_state[]">Pulau Pinang</label></li>
            <li><input type="checkbox" name="cp_state[]" value="Perak"  />&nbsp;<label for="cp_state[]">Perak</label></li>
            <li><input type="checkbox" name="cp_state[]" value="Sabah"  />&nbsp;<label for="cp_state[]">Sabah</label></li>
            <li><input type="checkbox" name="cp_state[]" value="Selangor"  />&nbsp;<label for="cp_state[]">Selangor</label></li>
            <li><input type="checkbox" name="cp_state[]" value="Sarawak"  />&nbsp;<label for="cp_state[]">Sarawak</label></li>
            <li><input type="checkbox" name="cp_state[]" value="Terengganu"  />&nbsp;<label for="cp_state[]">Terengganu</label></li>
        </ol> <!-- #checkbox-wrap -->
        </div> <!-- #end scrollbox -->
        </div> <!-- #end element -->
    <div class="clr"></div>
</li>