jQuery到纯javascript转换

Question

由于我没有使用任何外部库，我想将以下小提琴转换为非jQuery版本：this page

$(':text').keyup(function() {
    if($('#first_name').val() != "" && $('#second_name').val() != "") {
       $('#submit').removeAttr('disabled');
    } else {
       $('#submit').attr('disabled', true);   
    }
});

Answer 1

演示：http://jsfiddle.net/nc6NW/180/

var first = document.getElementById('first_name'),
    second = document.getElementById('second_name'),
    submit = document.getElementById('submit');
first.onkeyup = second.onkeyup = function() {
    submit.disabled = !(first.value && second.value);
};