2020-08-06 Source of topic: http://www.h-camel.com/index.html
[html] Please use canvas to draw an ellipse
1.ellipse(x, y, radiusX, radiusY, rotation, startAngle, endAngle, anticlockwise)
Starting point x. Starting point y, radius x, radius y, rotation angle, starting angle, result angle, clockwise or counterclockwise
2. The realization of Bezier curve is complicated and low precision
Refer to the 5 ways to draw an ellipse on canvas https://blog.csdn.net/gao xu 520/article/details/58588020
[css] Please give examples to illustrate the usage scenarios of width:fit-conten
css3 proposes the adaptive attribute value of widht
1.width: fit-content; indicates that the width will be reduced to the content width
2.width: fill-available; Indicates that the entire available space is filled, which is convenient for achieving contour layout height: fill-available;
3.width: max-content; Indicates that the maximum width of the internal element is used as the width of the container, for example, the text does not wrap
4.width: min-content; indicates that the minimum width of the internal element is used as the width of the container,
[js] Randomly generate a verification code of specified length
Idea: Specify the length as length, loop length times, and generate a random number from 0-9a-zA-Z each time.
Source: https://www.cnblogs.com/kenshinobiy/p/4894792.html
<html>
<head>
<title>验证码</title>
<style type="text/css">
#code {
font-family: Arial;
font-style: italic;
font-weight: bold;
border: 0;
letter-spacing: 2px;
color: blue;
width: 60px;
height: 24px;
}
</style>
</head>
<body onload="createCode()">
<div>
<input type="text" id="input" />
<input type="button" id="code" onclick="createCode()" />
<input type="button" value="验证" onclick="validate()" />
</div>
<script>
//在全局定义验证码
var code;
//产生验证码
function createCode() {
code = "";
var codeLength = 5; //验证码的长度
var checkCode = document.getElementById("code");
var random = new Array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K',
'L', 'M', 'N', 'O', 'P', 'Q', 'R',
'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'); //随机数
for (var i = 0; i < codeLength; i++) { //循环操作
var index = Math.floor(Math.random() * 36); //取得随机数的索引（0~35）
code += random[index]; //根据索引取得随机数加到code上
}
checkCode.value = code; //把code值赋给验证码
}
//校验验证码
function validate() {
var inputCode = document.getElementById("input").value.toUpperCase(); //取得输入的验证码并转化为大写
if (inputCode.length <= 0) { //若输入的验证码长度为0
alert("请输入验证码！"); //则弹出请输入验证码
} else if (inputCode != code) { //若输入的验证码与产生的验证码不一致时
alert("验证码输入错误！@_@"); //则弹出验证码输入错误
createCode(); //刷新验证码
document.getElementById("input").value = ""; //清空文本框
} else { //输入正确时
alert("^-^"); //弹出^-^
}
}
</script>
</body>
</html>
[Soft skills] We often use the ping command. Do you know its function and principle?
The principle of Ping is the ICMP protocol, and the full name of ICMP is Intent Control Message Protocol, which comes from Chinese as Internet Control Message Protocol;
Reference article https://blog.csdn.net/zhangyexinaisurui/article/details/82939401