1. 核心：控制 数量的长度-1-i的位置，是放在left上还是top上？是放在前面还是后面！
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>自动生成各种图案的小方块</title>
<style>
*{margin:0; padding: 0;}
body{background-color: #cccccc;}
.container{600px; height:600px; background-color: #fff; margin: 0 auto}
.button{position:absolute; margin-left: 1000px; margin-top: -600px;}
.button ul{list-style-type: none}
.button ul li{display:block; height:40px;background: #069DD5; border-radius: 5px; margin-top: 10px; line-height: 40px;}
.button ul li a{text-decoration: none; color:#fff;}
#show{list-style-type: none;}
#show li{display:block; 50px; height:50px; position:absolute;text-align: center;margin:5px; line-height: 40px}
</style>
</head>
<body>
<script>
window.onload = function () {
var aBtnLi = document.getElementsByTagName('li');
for(var i = 0; i < aBtnLi.length; i++){ //鼠标移入移出效果
aBtnLi[i].onmouseover = function () {
this.style.background = "#272822";
}
aBtnLi[i].onmouseout = function () {
this.style.background = "#069DD5";
}
}
var colors = ['red','green','blue','gray','yellow'];
var colorLen = colors.length;
var oShow = document.getElementById('show');
//1.自动生成10个方块, 每个left增加60px; top值不变 ！
var show10 = '';
aBtnLi[0].onclick = function () {
oShow.innerHTML = ''; //打扫桌子，等待下桌客人
for(var i = 0; i < 10; i++){
show10 += "<li style='background:"+ colors[i % colorLen] + ";left:" + 60 * (i % 10) +"px;top:" + 60 * parseInt(i / 10)+"px;'>"+ i +"</li>";
}
oShow.innerHTML = show10;
}
//2.自动生成100个方块， i % 10 决定了每行十个； 60 * parseInt(i / 10)决定了第几行
var show100 = '';
aBtnLi[1].onclick = function () {
oShow.innerHTML = '';
for(var i = 0; i < 100; i++){
show100 += "<li style='background:"+ colors[i % colorLen]+";left:" + 60 * (i % 10)+ "px;top:" + 60 * parseInt(i / 10)+"px;'>"+ i +"</li>";
}
oShow.innerHTML = show100;
}
//3. 生成阶梯状方块
var stair = '';
aBtnLi[2].onclick = function () {
oShow.innerHTML = '';
for(var i = 0; i < 10; i++) {
stair += "<li style='background:"+ colors[i % colorLen] + ";left:" + 60 * (i % 10) + "px;top:"+ 60 * i + "px;'>"+ i +"</li>";
}
oShow.innerHTML = stair;
}
//4. 生成正V 核心：上下V 控制top值的变化；
var strV = '';
aBtnLi[3].onclick = function () {
oShow.innerHTML = '';
for(var i = 0; i < 9; i++) {
if ( i < 5) { // left 变大； top值变大
strV += "<li style='background:"+ colors[i % colorLen] + ";left:" + 60 * (i % 10) + "px;top:"+ 60 * i + "px;'>"+ i +"</li>";
} else{ // left变大； top值变小
strV += "<li style='background:"+ colors[i % colorLen] + ";left:" + 60 * (i % 10) + "px;top:"+ 60 * (8 - i) + "px;'>"+ i +"</li>";
}
}
oShow.innerHTML = strV;
}
//5. 生成倒V
var oppsiteV = '';
aBtnLi[4].onclick = function () {
oShow.innerHTML = "";
for(var i = 0; i < 9; i++) {
if ( i < 5) { // 围绕5旋转 left变大 top变小
oppsiteV += "<li style='background:"+ colors[i % colorLen] + ";left:" + 60 * (i % 10) + "px;top:"+ 60 * (8 - i) + "px;'>"+ i +"</li>";
} else{ // left变大 top变大
oppsiteV += "<li style='background:"+ colors[i % colorLen] + ";left:" + 60 * (i % 10) + "px;top:"+ 60 * i + "px;'>"+ i +"</li>";
}
// if ( i < 5) { //从顶点开始
// oppsiteV += "<li style='background:"+ colors[i % colorLen] + ";left:" + 60 * (i % 10) + "px;top:"+ 60 * (4 - i) + "px;'>"+ i +"</li>";
// } else {
// oppsiteV += "<li style='background:"+ colors[i % colorLen] + ";left:" + 60 * (i % 10) + "px;top:"+ 60 * (i - 5) + "px;'>"+ i +"</li>";
// }
}
oShow.innerHTML = oppsiteV;
}
//6. 生成大于号V 核心原理：左右V控制的left变化
var greaterThanV = '';
aBtnLi[5].onclick = function () {
oShow.innerHTML = '';
for(var i = 0; i < 9; i++) {
if ( i < 5) { //前5个 left值变大，top值变大
greaterThanV += "<li style='background:"+ colors[i % colorLen] + ";left:" + 60 * (i % 10) + "px;top:"+ 60 * i + "px;'>"+ i +"</li>";
} else{ //left变小， top变大
greaterThanV += "<li style='background:"+ colors[i % colorLen] + ";left:" + 60 * (8 - i) + "px;top:"+ 60 * i + "px;'>"+ i +"</li>";
}
}
oShow.innerHTML = greaterThanV;
}
//7. 生成小于号V
var lowerThanV = '';
aBtnLi[6].onclick = function () {
oShow.innerHTML = '';
for(var i= 0; i < 9; i++) {
if ( i < 5) { //left值变小，top变大
lowerThanV += "<li style='background:"+ colors[i % colorLen] + ";left:" + 60 * (8 - i) + "px;top:"+ 60 * i + "px;'>"+ i +"</li>";
} else { //left值变大，top值变大
lowerThanV += "<li style='background:"+ colors[i % colorLen] + ";left:" + 60 * (i % 10) + "px;top:"+ 60 * i + "px;'>"+ i +"</li>";
}
}
oShow.innerHTML = lowerThanV;
}
}
</script>
<div class="container">
<div style="position: relative">
<ul id="show"></ul>
</div>
</div>
<div class="button">
<ul>
<li><a href="#">自动生成10个方块</a></li>
<li><a href="#">自动生成100个方块</a></li>
<li><a href="#">自动生成阶梯状方块</a></li>
<li><a href="#">自动生成正V型方块</a></li>
<li><a href="#">自动生成倒V型方块</a></li>
<li><a href="#">自动生成>型方块</a></li>
<li><a href="#">自动生成<型方块</a></li>
</ul>
</div>
</body>
</html>