Question

What is wrong/missing in my code.
I’m trying to makemultiple selections in options using multiple data concatenated from a string.

var nidText = "a;b;c;d"

var nidData = nidText.split(';');

$('#selectId option[value=' + nidData + ']').attr('selected', true);

Answer 1

In your code, the nidData is an array! Not a string. So you need to use $.each or some looping function.

$(document).ready(function(){
    var nidText = "a;b;c;d";
    var nidData = nidText.split(';');
    for (var nidDat in nidData)
        $('#selectId option[value="' + nidData[nidDat] + '"]').prop('selected', true);
});

Fiddle: http://jsfiddle.net/fbCeL/