0plus1 Blog

This is a simple function to append values to a multiselect. In the comments you’ll find the explanation of each command.

function appendMulti(value,target){
    //Get old values from multiselect (they are an array)
	oldvalues= $(target).val();
	//We need to check if the multiselect is empty
	if(oldvalues){
        //It's not empty
		//Find the lenght of the array, the beauty of this is that since arrays starts from 0, this number will always be the next available slot
		key = value.length;
	} else {
        //It's empty
		//Initialize a new array and set the key to the first element
		var oldvalues = [];
		key = 0;
	}
	//Append new value to the array
	oldvalues[key] = value;
	//Set the new values
	$(target).val(oldvalues);

	return true;
}

You can call the function like this:

appendMulti('value','#multiselect');