<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>IFE ECMAScript</title>
</head>
<body>
<input id="first-number" type="number" value="0" placeholder="第一个数字">
<input id="second-number" type="number" value="0" placeholder="第二个数字">
<button id="add-btn">加</button>
<button id="minus-btn">减</button>
<button id="times-btn">乘</button>
<button id="divide-btn">除</button>
<p id="result">运算结果</p>
<script>
window.onload = function(){
var arr = document.getElementsByTagName(‘button‘);
var getid;
for(var i = 0;i<arr.length;i++)
{
arr[i].onclick = function()
{
var x = parseFloat(document.getElementById("first-number").value),
y = parseFloat(document.getElementById("second-number").value);
if(isNaN(x) || isNaN(y)){
console.log("输入存在非数字");
}
getid = this.id;
if(getid === "divide-btn" && y=== 0){
alert("除数不能为0");
console.log("除数为0");}
switch(getid)
{
case "add-btn":result.innerHTML = x + y;break;
case "minus-btn":result.innerHTML = x - y;break;
case "times-btn":result.innerHTML = x * y;break;
case "divide-btn":result.innerHTML = x / y;break;
}
}
}
}
</script>
</body>
</html>
二进制转换代码：
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>IFE ECMAScript</title>
</head>
<body>
<input id="dec-number" type="number" placeholder="输入一个十进制非负整数">
<button id="trans-btn">转化为二进制</button>
<p id="result">运算结果</p>
<script>
function dec2bin(decNumber) {
// 在这里实现你的转化方法，注意需要判断输入必须为一个非负整数
if(isNaN(decNumber)||decNumber<0){
console.log(decNumber);
alert("请输入合法数字");
return false;
}
else{
decNumber=parseInt(decNumber);
var num2 = decNumber.toString(2);
return num2;
}
}
// 实现当点击转化按钮时，将输入的十进制数字转化为二进制，并显示在result的p标签内
document.getElementById("trans-btn").onclick = function(){
var num = dec2bin(document.getElementById("dec-number").value);
document.getElementById("result").innerHTML = num;
}
// Some coding
</script>
</body>
</html>
二进制转换加强版：
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>IFE ECMAScript</title>
</head>
<body>
<input id="dec-number" type="number" placeholder="输入一个十进制非负整数">
<input id="bin-bit" type="number" placeholder="输入转化后二进制数字位数">
<button id="trans-btn">转化为二进制</button>
<p id="result">运算结果</p>
<script>
function dec2bin(decNumber) {
// 在这里实现你的转化方法，注意需要判断输入必须为一个非负整数
// 这里是上一个任务的实现
var y="";
if(isNaN(decNumber)||decNumber<0){
console.log(decNumber);
alert("请输入合法数字");
return false;
}
else{
decNumber=parseInt(decNumber);
var num2 = decNumber.toString(2);
return num2;
}
}
// 实现当点击转化按钮时，将输入的十进制数字转化为二进制，并显示在result的p标签内
document.getElementById("trans-btn").onclick = function(){
var num = dec2bin(document.getElementById("dec-number").value);
//获取数字二进制长度
var numlength = num.length;
// 新的需求是，转化显示后的二进制数为bin-bit中输入的数字宽度，例如
// dec-number为5，bin-bit为5，则转化后数字为00101
var length = document.getElementById("bin-bit").value;
// 当二进制长度小于要求长度时，前面+0;
while(numlength<length){
num ="0"+num;
numlength++;
}
document.getElementById("result").innerHTML = num;
// 如果bin-bit小于转化后的二进制本身位数，则使用原本的位数，如dec-number为5，bin-bit为2，依然输出101，但同时在console中报个错
if(numlength>length){
console.log("警告！！！bin-bit小于转化后的二进制本身位数");
}
}
// Some coding
</script>
</body>
</html>
3的游戏：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>判断3的倍数或者含3</title>
</head>
<body>
<p id="result">运算结果</p>
<script>
function judgeThree(){
var num = new Array();
for(var i=0;i<100;i++){
num[i] = i+1;
}
for(var i=0;i<num.length;i++){
if(num[i]%3 == 0 || (num[i].toString()).indexOf(‘3‘) ==1){
num[i] = ‘PA‘;
document.getElementById("result").innerHTML = num;
}
}
console.log(num.join());
}
judgeThree();
</script>
</body>
</html>
小九九代码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>九九乘法表</title>
</head>
<body onload="a()">
<table id="table">
</table>
<script>
function a(){
var t = document.getElementById("table");
for(i=9;i>0;i--){
var tr = document.createElement("tr")
for(j=1;j<i+1;j++){
var td = document.createElement("td");
var node = document.createTextNode(j+‘*‘+i+‘=‘+j*i);
td.appendChild(node);
tr.appendChild(td);
t.appendChild(tr);
}
}
}
</script>
</body>
</html>
根据系统生成时间问候语：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>根据系统时间生成问候语</title>
</head>
<body>
<button id="time">点击这里看时间</button>
<p id="demo"></p>
<script>
document.getElementById("time").onclick = function(){
var x ="";
var time = new Date().getHours();
if(time>20){
x = "现在是晚上了呢亲，早点睡觉哦";
}
if(time<12){
x = "早上好啊";
}
if(time>12 && time<14){
x = "中午好啊";
}if(time>14 && time<20){
x = "下午好啊";
}
document.getElementById("demo").innerHTML = x;
}
</script>
</body>
</html>
