JavaScript - how to change item from drop-down menu

Question

how to change select item from drop-down menu by JavaScript

<select name="example_length" aria-controls="example" class="">
<option value="10">10</option>
<option value="25">25</option>
<option value="50">50</option>
<option value="100">100</option>
</select>

I tried to change value of drop-down menu by:

document.getElementsByName("example_length")[0].value=100   

but number only cahanged in HTML but content not changed ;

link to example Table Sorting

Answer 1

i found answer

by plain JavaScript

document.getElementsByName("example_length")[0].value = 50;
var event = new Event('change');
document.getElementsByName("example_length")[0].dispatchEvent(event);

by jQuery

$( "select[name='example_length']" ).val(50).change();