Add and delete options dynamically in JS

1. dynamically create selectfunctioncreateSelect () {varmySelectdocument. createElement (& quot; select & quot;); mySelect. id & quot; mySelect & quot; document. body. appendChild (mySelect);} 2. 1. dynamically create select function createSelect () {var mySelect = document. createElement ("select"); mySelect. id = "mySelect"; document. body. appendChild (mySelect);} 2. add option function addOption () {// search for objects by id, var obj = document. getElementById ('myselect'); // Add an option obj. add (new Option ("text", "value"); // This is only valid in IE. options. add (new Option ("text", "value"); // compatible with IE and firefox} 3. delete all options option function removeAll () {var obj = document. getElementById ('myselect'); obj. options. length = 0;} 4. delete an optional optionfunction removeOne () {var obj = document. getElementById ('myselect'); // index. The sequence number of the option to be deleted. The number var index = obj of the selected option is used here. selectedIndex; obj. options. remove (index);} 5. obtain the option value var obj = document. getElementById ('myselect'); var index = obj. selectedIndex; // The serial number. The serial number var val = obj. options [index]. value; 6. obtain the option text var obj = document. getElementById ('myselect'); var index = obj. selectedIndex; // The serial number. The serial number var val = obj. options [index]. text; 7. modify optionvar obj = document. getElementById ('myselect'); var index = obj. selectedIndex; // The serial number. The serial number var val = obj. options [index] = new Option ("new text", "new Value"); 8. delete select function removeSelect () {var mySelect = document. getElementById ("mySelect"); mySelect. parentNode. removeChild (mySelect);} the complete code for the entire instance is as follows: