Lazy Option

gistfile1.js

function findKeyword(event) {
  var strKeyword = prompt('Input the Keyword what you want to search.');
  var opts = this.options;
  var matchIndex = [];
  for(var i = 0; i < opts.length; i++) {
    if(opts[i].text.indexOf(strKeyword) != -1) matchIndex.push(i);
  }
  switch(matchIndex.length) {
  case 0:
    alert('Not found.');
    break;
  case 1:
    this.options[matchIndex[0]].selected = true;
    break;
  default:
    var tmp = 'Found too many keywords.\nPlz choose below options.\n';
    for(var i = 0; i < matchIndex.length; i++) {
      tmp += '[' + i + '] ' + this.options[matchIndex[i]].text + '\n';
    }
    var index = prompt(tmp);
    this.options[matchIndex[index]].selected = true;
  }
}
var selectEles = document.getElementsByTagName('select');
for(var i = 0; i < selectEles.length; i++)
  selectEles[i].addEventListener('focus', findKeyword, false);