练习3:闪烁的方块

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<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style>
#container {
width: 800px;
height: 400px;
margin: 10px auto;
border: 1px solid black;
overflow: hidden;
}
#buttons {
width: 800px;
margin: 10px auto;
text-align: center;
}
#add, #fla {
border: none;
outline: none;
width: 80px;
height: 30px;
background-color: red;
color: white;
font-size: 16px;
cursor: pointer;
}
.small {
width: 80px;
height: 80px;
float: left;
}
</style>
</head>
<body>
<div id="container"></div>
<div id="buttons">
<button id="add">添加</button>
<button id="fla">闪烁</button>
</div>
<script src="js/mylib.js"></script>
<script>
var bigDiv = document.querySelector('#container');
var addButton = document.querySelector('#add');
addButton.addEventListener('click', function() {
var smallDiv = document.createElement('div');
smallDiv.className = 'small';
// smallDiv.style.width = '80px';
// smallDiv.style.height = '80px';
// smallDiv.style.float = 'left';
smallDiv.style.backgroundColor = randomColor();
bigDiv.insertBefore(smallDiv, bigDiv.firstChild);
});
var flaButton = document.querySelector('#fla');
var isFlashing = false;
var timerId;
flaButton.addEventListener('click', function(evt) {
isFlashing = !isFlashing;
if (isFlashing) {
timerId = window.setInterval(function() {
var divs = document.querySelectorAll('#container>div');
for (var i = 0; i < divs.length; i += 1) {
divs[i].style.backgroundColor = randomColor();
}
}, 200);
flaButton.textContent = '暂停';
} else {
window.clearInterval(timerId);
flaButton.textContent = '闪烁';
}
});
</script>
</body>
</html>