Question

I am passing a value to the dropdownlist, how to get the index of the value of the dropdownlist and set it using javascript?

 document.getElementById("ddlColors").selectedIndex = ?

Thank you

Answer 1

A loop is the only way, really:

var options = document.getElementById('ddlColors').options;

for(var i = 0; i < options.length; i++) {
    if(options[i].value === someValue) {
        options[i].selected = true;
        break;
    }
}

Here’s a demo.