Input autocomplete with ajax

autocomplete.js

// jQuery UI is required

$("#target_input").autocomplete({
  minLength: 2,
  source: "ajax/autocomplete.php", // expects JSON
  select: function(event, ui) {
    $("#target_input").val(ui.item.label); // display the selected text
    $("#target_input-id").val(ui.item.value); // save selected id to hidden input
    event.preventDefault(); // prevent autocomplete from updating the textbox
    return false; // prevent from inserting id into the input instead of label
  },
  // To prevent inserting ID instead of label when you press the down the arrows:
  focus: function(event){
    event.preventDefault();
  }
});