jQuery operation memo record for Select_jquery

jQuery gets the Text and Value selected by Select:

Syntax explanation:
1. $("#select_id").change(function(){//code...} ); //Add an event for Select, triggered when one of the items is selected
2. var checkText=$("#select_id").find("option:selected").text(); //Get the Select selection Text
3. var checkValue=$("#select_id").val(); //Get the Value selected by Select
4. var checkIndex=$("#select_id ").get(0). selectedIndex; //Get the index value selected by Select
5. var maxIndex=$("#select_id option:last").attr("index"); //Get the maximum index value of Select

jQuery sets the Text and Value selected by Select:

Syntax explanation:
1. $("#select_id ").get(0).selectedIndex=1; //Set Select The item with index value 1 is selected
2. $("#select_id ").val(4); //Set the Select Value to 4 and the item is selected
3. $("#select_id option[text ='jQuery']").attr("selected", true); //Set the Text value of Select to the jQuery item selected

jQuery adds/removes the Option item of Select:

Syntax explanation:
1. $("#select_id").append("Text"); //Append an Option (drop-down item) to Select
2 . $("#select_id").prepend("Please select "); //Insert an Option (first position) for Select
3. $("#select_id option:last" ).remove(); //Delete the Option with the largest index value in Select (the last one)
4. $("#select_id option[index='0']").remove(); //Delete the index in Select Option with value 0 (first)
5. $("#select_id option[value='3']").remove(); //Remove Option with Value='3' in Select
6. $("#select_id option[text='4']").remove(); //Delete the Option with Text='4' in Select