set dropdown value by text using jquery [duplicate]

This is a method that works based on the text of the option, not the index. Just tested.

var theText = "GOOGLE";
$("#HowYouKnow option:contains(" + theText + ")").attr('selected', 'selected');

Or, if there are similar values (thanks shanabus):

$("#HowYouKnow option").each(function() {
  if($(this).text() == theText) {
    $(this).attr('selected', 'selected');            
  }                        
});

For the exact match use

    $("#HowYouKnow option").filter(function(index) { return $(this).text() === "GOOGLE"; }).attr('selected', 'selected');

contains is going to select the last match which might not be exact.

$("#HowYouKnow option[value='" + theText + "']").attr('selected', 'selected'); // added single quotes