JS operations select form Daquan, assign default value, value, add, delete, etc.

It is best to add this sentence before all the following code:

1	var selectId=document.getElemengById('selectId');

Clear select items

1	selectId.options.length = 0;

If the first line is left

1	selectId.options.length = 1;

Add an option to the select option

123	VaR varoption = New Option (objoptiontext, objoptionvalue); selectid. Options [selectid. Options. Length] = varoption; // or selectid. Options. Add (varoption );

Delete An option from the select option

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for(var i=0;i<selectId.options.length;i++) { if(selectId.options[i].value == objOptionValue) { selectId.options.remove(i); break; } }

Set the first option of text = "paratext" in select to select

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for(var i=0;i<selectId.options.length;i++) { if(selectId.options[i].text == objOptionText) { selectId.options[i].selected = true; isExit = true; break; } }

Set option of value = "paravalue" in select to select

1	selectId.value = objOptionValue;

Obtain the value of the selected item in the SELECT statement.

1	var currSelectValue = selectId.value;

Obtain the text of the selected item in the SELECT statement.

1	var currSelectText = selectId.options[selectId.selectedIndex].text;

Returns the index of the selected item in the SELECT statement.

1	var currSelectIndex = selectId.selectedIndex;