Country Select – On Change Country Flag Image Transition

<img id="flag" src="images/flags/pk.png"/>
<select onchange="if(document.images) document.images['flag'].src='images/flags/'+this.options[this.selectedIndex].value+'.png';" name="country">
<option selected="selected" value="pk">Pakistan</option>
<option value="af">Afghanistan</option>
<option value="al">Albania</option>
<option value="dz">Algeria</option>
<option value="as">American Samoa</option>
<option value="ad">Andorra</option>
<option value="ao">Angola</option>
<option value="ai">Anguilla</option>
<option value="aq">Antarctica</option>
<option value="ag">Antigua and Barbuda</option>
<option value="ar">Argentina</option>
<option value="am">Armenia</option>
<option value="arpa">Arpanet</option>
<option value="aw">Aruba</option>
<option value="au">Australia</option>
<option value="at">Austria</option>
<option value="az">Azerbaijan</option>
<option value="bs">Bahamas</option>
<option value="bh">Bahrain</option>
<option value="bd">Bangladesh</option>
<option value="bb">Barbados</option>
<option value="by">Belarus</option>
<option value="be">Belgium</option>
<option value="bz">Belize</option>
<option value="bj">Benin</option>
<option value="bm">Bermuda</option>
<option value="bt">Bhutan</option>
<option value="bo">Bolivia</option>
<option value="ba">Bosnia and Herzegovina</option>
<option value="bw">Botswana</option>
<option value="bv">Bouvet Island</option>
<option value="br">Brazil</option>
<option value="io">British Indian Ocean Territory</option>
<option value="bn">Brunei Darussalam</option>
<option value="bg">Bulgaria</option>
<option value="bf">Burkina Faso</option>
<option value="bi">Burundi</option>
<option value="kh">Cambodia</option>
<option value="cm">Cameroon</option>
<option value="ca">Canada</option>
<option value="cv">Cape Verde</option>
<option value="ky">Cayman Islands</option>
<option value="cf">Central African Republic</option>
<option value="td">Chad</option>
<option value="cl">Chile</option>
<option value="cn">China</option>
<option value="cx">Christmas Island</option>
<option value="cc">Cocos (Keeling) Islands</option>
<option value="co">Colombia</option>
<option value="km">Comoros</option>
<option value="cg">Congo</option>
<option value="ck">Cook Islands</option>
<option value="cr">Costa Rica</option>
<option value="hr">Croatia (Hrvatska)</option>
<option value="cu">Cuba</option>
<option value="cy">Cyprus</option>
<option value="cz">Czech Republic</option>
<option value="cs">Czechoslovakia (former)</option>
<option value="dk">Denmark</option>
<option value="dj">Djibouti</option>
<option value="dm">Dominica</option>
<option value="do">Dominican Republic</option>
<option value="tp">East Timor</option>
<option value="ec">Ecuador</option>
<option value="eg">Egypt</option>
<option value="sv">El Salvador</option>
<option value="gq">Equatorial Guinea</option>
<option value="er">Eritrea</option>
<option value="ee">Estonia</option>
<option value="et">Ethiopia</option>
<option value="eu">Europe</option>
<option value="fk">Falkland Islands (Malvinas)</option>
<option value="fo">Faroe Island</option>
<option value="fj">Fiji</option>
<option value="fi">Finland</option>
<option value="fr">France</option>
<option value="gf">French Guiana</option>
<option value="pf">French Polynesia</option>
<option value="tf">French Southern Territories</option>
<option value="ga">Gabon</option>
<option value="gm">Gambia</option>
<option value="ge">Georgia</option>
<option value="de">Germany</option>
<option value="gh">Ghana</option>
<option value="gi">Gibraltar</option>
<option value="gb">Great Britain (UK)</option>
<option value="gr">Greece</option>
<option value="gl">Greenland</option>
<option value="gd">Grenada</option>
<option value="gp">Guadeloupa</option>
<option value="gu">Guam</option>
<option value="gt">Guatemala</option>
<option value="gn">Guinea</option>
<option value="gw">Guinea-Bissau</option>
<option value="gy">Guyana</option>
<option value="ht">Haiti</option>
<option value="hm">Heard and McDonald Islands</option>
<option value="hn">Honduras</option>
<option value="hk">Hong Kong</option>
<option value="hu">Hungary</option>
<option value="is">Iceland</option>
<option value="in">India</option>
<option value="id">Indonesia</option>
<option value="int">International</option>
<option value="ir">Iraq</option>
<option value="iq">Iran</option>
<option value="ie">Ireland</option>
<option value="il">Israel</option>
<option value="it">Italy</option>
<option value="jm">Jamaica</option>
<option value="jp">Japan</option>
<option value="jo">Jordan</option>
<option value="kz">Kazakhstan</option>
<option value="ke">Kenya</option>
<option value="ki">Kiribati</option>
<option value="kp">Korea (North)</option>
<option value="kr">Korea (South)</option>
<option value="kw">Kuwait</option>
<option value="kg">Kyrgyzstan</option>
<option value="la">Laos</option>
<option value="lv">Latvia</option>
<option value="lb">Lebanon</option>
<option value="ls">Lesotho</option>
<option value="lr">Liberia</option>
<option value="ly">Libya</option>
<option value="li">Liechtenstein</option>
<option value="lt">Lithuania</option>
<option value="lu">Luxembourg</option>
<option value="mo">Macau</option>
<option value="mk">Macedonia</option>
<option value="mg">Madagascar</option>
<option value="mw">Malawi</option>
<option value="my">Malaysia</option>
<option value="mv">Maldives</option>
<option value="ml">Mali</option>
<option value="mt">Malta</option>
<option value="mh">Marshall Islands</option>
<option value="mq">Martinique</option>
<option value="mr">Mauritania</option>
<option value="mu">Mauritius</option>
<option value="yt">Mayotte</option>
<option value="mx">Mexico</option>
<option value="fm">Micronesia</option>
<option value="md">Moldova</option>
<option value="mc">Monaco</option>
<option value="mn">Mongolia</option>
<option value="ms">Montserrat</option>
<option value="ma">Morocco</option>
<option value="mz">Mozambique</option>
<option value="mm">Myanmar</option>
<option value="na">Namibia</option>
<option value="nr">Nauru</option>
<option value="np">Nepal</option>
<option value="nl">Netherlands</option>
<option value="an">Netherlands Antilles</option>
<option value="nc">New Caledonia</option>
<option value="nz">New Zealand (Aotearoa)</option>
<option value="ni">Nicaragua</option>
<option value="ne">Nigee</option>
<option value="ng">Nigeria</option>
<option value="nu">Niue</option>
<option value="nf">Norfolk Island</option>
<option value="mp">Northern Mariana Islands</option>
<option value="no">Norway</option>
<option value="om">Oma</option>
<option value="pk">Pakistan</option>
<option value="pw">Palau</option>
<option value="pa">Panama</option>
<option value="pg">Papua New Guinea</option>
<option value="py">Paraguay</option>
<option value="pe">Peru</option>
<option value="ph">Philippines</option>
<option value="pn">Pitcairn</option>
<option value="pl">Poland</option>
<option value="pt">Portugal</option>
<option value="pr">Puerto Ric</option>
<option value="qa">Qatar</option>
<option value="re">Reunion</option>
<option value="ro">Romania</option>
<option value="ru">Russia</option>
<option value="rw">Rwanda</option>
<option value="gs">S. Georgia and S. Sandwich Isls</option>
<option value="kn">Saint Kitts and Nevis</option>
<option value="lc">Saint Lucia</option>
<option value="vc">Saint Vincent and the Grenadines</option>
<option value="ws">Samoa</option>
<option value="sm">San Marino</option>
<option value="st">Sao Tome and Principe</option>
<option value="sa">Saudi Arabia</option>
<option value="sn">Senegal</option>
<option value="rs">Serbia</option>
<option value="sc">Seychelles</option>
<option value="sl">Sierra Leone</option>
<option value="sg">Singapore</option>
<option value="sk">Slovak Republic</option>
<option value="si">Slovenia</option>
<option value="sb">Solomon Islands</option>
<option value="so">Somalia</option>
<option value="za">South Africa</option>
<option value="es">Spain</option>
<option value="lk">Sri Lanka</option>
<option value="sh">St. Helena</option>
<option value="pm">St. Pierre and Miquelon</option>
<option value="sd">Sudan</option>
<option value="sr">Suriname</option>
<option value="sj">Svalbard and Jan Mayen Islands</option>
<option value="sz">Swaziland</option>
<option value="se">Sweden</option>
<option value="ch">Switzerland</option>
<option value="sy">Syria</option>
<option value="tw">Taiwan</option>
<option value="tj">Tajikistan</option>
<option value="tz">Tanzania</option>
<option value="th">Thailand</option>
<option value="tg">Togo</option>
<option value="tk">Tokelau</option>
<option value="to">Tonga</option>
<option value="tt">Trinidad and Tobago</option>
<option value="tn">Tunisia</option>
<option value="tr">Turkey</option>
<option value="tm">Turkmenistan</option>
<option value="tc">Turks and Caicos Islands</option>
<option value="tv">Tuvalu</option>
<option value="ug">Uganda</option>
<option value="ua">Ukraine</option>
<option value="ae">United Arab Emirates</option>
<option value="uk">United Kingdom</option>
<option value="us">United States</option>
<option value="uy">Uruguay</option>
<option value="um">US Minor Outlying Islands</option>
<option value="su">USSR (former)</option>
<option value="uz">Uzbekistan</option>
<option value="vu">Vanuat</option>
<option value="va">Vatican City State (Holy See)</option>
<option value="ve">Venezuela</option>
<option value="vn">Viet Nam</option>
<option value="vg">Virgin Islands (British)</option>
<option value="vi">Virgin Islands (U.S.)</option>
<option value="wf">Wallis and Futuna Islands</option>
<option value="eh">Western Sahara</option>
<option value="ye">Yemem</option>
<option value="zr">Zaier</option>
<option value="zm">Zambia</option>
<option value="zw">Zimbabwe</option>
</select>