我如何使用javascript在输入选择（HTML）中设置字段？

Question

我将随机选择一个数字，并在带有排序数字的选择中定义所选字段。我如何设置该字段？

Answer 1

将selected selected =“selected”添加到要选择的选项元素中。

伪代码

function foo()
{
create list of option elements
generate random number
get a single option element at index of random number
set all options attribute "selected" = null
set the option element[at index of random number] attribute selected = "selected"
}

Answer 2

var randomNumber = 3; // just for example 
document.getElementById('select_field').selectedIndex = randomNumber;