// query selector
var header = document.querySelector('#main-header');
header.style.boarderBottom = "solid 4px #ccc";

var input = document.querySelector('input');
input.value = "Hello World"; // 直接修改input框的數值
var submit = document.querySelector('input[type="submit"]')
submit.value = "SEND";

var item =
 
 document.querySelector('.list-group-item');
item.style.color = 'red';

var item = document.querySelector('.list-group-item:last-child');
item.style.color = 'blue';

var item = document.querySelector('.list-group-item:nth-child(2)')
item.style.color = "coral";


/* query selector all */
var titles = document.
 
querySelectorAll('.title');
console.log(titles);
titles[0].textContent = "Hello";
titles[1].textContent = "World";

var odd = document.querySelectorAll('li:nth-child(odd)');
var even = document.querySelectorAll('li:nth-child(even)');

// odd.style.backgroundColor = 'gray';
console.log(odd);
odd.forEach
 
(function(item){
	item.style.backgroundColor = "#f4f4f4";
});

even.forEach(function(item) {
	item.style.backgroundColor = '#ccc';
});

程式碼庫。

END.