String
Javascript String is the built-in objects, attributes and operations which provides processing of the string
- length property: obtaining length of the string
- the toLowerCase () and toUpperCase: it is converted to a string of uppercase and lowercase
- charAt (): Returns a string of characters specified index
- indexOf: from left to right to find in the string specified string and returns the subscript, is not found, returns -1
- lastIndexOf: in the string specified search string from right to left, only to find the first occurrence of
- substr (): Returns the specified length starting from a specified position of the substring
- substring (): for extracting a character string of an intermediary between the two specified index
- split (): striped array, after completion of a sub-array is a
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>js-数组--字符串</title>
<script type="text/javascript">
// 计算字符串的长度：length
var str1 = '我们一起学python';
var len = str1.length;
document.write('字符串：'+str1+'<br />长度为:'+len)
//将字符串大小写转换toLowerCase()----toUpperCase()
var str2 = 'Java--PYTHON'
document.write('全小写'+str2.toLowerCase());
document.write('<br />全大写'+str2.toUpperCase());
//返回数组的下标 CharAt(index) :index是字符串的下标
var str3 = 'python----Java';
document.write('<br />'+str3.charAt(0));
document.write('<br />'+str3.charAt(str3.length-1));
//indexOf() : 在原始字符串中，从左往右查找指定的字符串，找到之后，返回下标值，没有则返回-1
var str4 = "Life is short. I'm learning python....";
var index = str4.indexOf('python');
if (index == -1){
document.write('<br />不存在....')
}else{
document.write('<br />存在.....')
}
// 从原始字符串中提取指定的字符串 substr(索引号)
var str5 = "Life is short. I'm learning python....";
var x = str5.substr(5);
var y = str5.substr(4,8);
document.write('<br />下标为5之后的元素 '+x)
document.write('<br />下标4-8的字符 '+y);
// substring
var str5 = "Life is short. I'm learning python....";
var m = str.substring(0,3);
var n = str.substring(0,5);
document.write('<br />下标为0--3之后的元素 '+m)
document.write('<br />下标0--5的字符 '+n);
</script>
</head>
<body>
</body>
</html>
Small Case (input file name to determine whether the picture)
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>js-operation</title>
<script type="text/javascript">
// 输入一个文件名称判断是否是图片格式
function isImage(){
//创建一个图片格式的数组
var img = ['.png','.jpg','.gif'];
// var img_name = window.prompt('输入一个文件名称:')
var img_name = '123.jpg';
// 获取拿到的文件名称的扩展名的.的位置
var img_index = img_name.lastIndexOf('.');
// 以.为界限，拿取后边的扩展名
var img_name_ext = img_name.substr(img_index+1);
// 循环开始判断
for (var i=0;i<img.length;i++){
if (img_name_ext == img[i]){
return true;
}
}return false；
}
//判断上传文件是否是图片
if(isImage())
{
document.write("是图片格式.....");
}else
{
document.write("不是图片格式........");
}
</script>
</head>
<body>
</body>
</html>
Array (i.e., array)
- The length property
- join (): the elements of the array into a string of splicing
- delete: delete elements of the value of its length unchanged
- shift: removes a first value of the element, its length minus 1
- pop (): Delete the last element, length minus 1, the return value of the deleted
- reserve (): an array in reverse
The following example demonstrates the use of a method to
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>案例</title>
<script type="text/javascript">
// （字符，偏难）利用var s1 = prompt(“请输入任意字符”,””)可以获取用户输入的字符(输入一个字符串含有符号和数字)，试编程将用户输入的字符“反转顺序”并首尾字母转为大写，其他字母转为小写后alert出来,数字和字符删除。
// 1.获取用户输入的字符串
// 2.将输入的字符串通过分割的方法转化数组
// 3.定义一个数组存储26个英文字母
// 4.创建一个新的数组对象，存储之后拿到的字母
// 5.通过循环比较输入的字符串转化的数组和存储26个字母的数组中相等的则添加到新的数组中
// 6.将数组反转,反转之后重新转化为字符串
// 7.然后将字符串全部转化为小写
// 8.重新转化为数组，然后首尾大写，之后转化为字符串则完成
// 用户输入一个字符串
var str1 = window.prompt('输入一串字符串(包含数字特殊字符):')
document.write('<h2>输入的字符串为：'+str1+'</h2><br /><br />');
// 通过分割转化为数组
var arr_list = str1.split('');
// 定义一个数组存储字母
var letter = [
'a','b','c','d','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z',
'A','B','C','D','E','F','G','H','I','J','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z']
// 定义一个数组保存字母
var arr_list1 = new Array;
// 循环
for (var i=0;i<arr_list.length;i++){
for (var j=0;j<letter.length;j++){
if (arr_list[i] == letter[j]){
arr_list1.push(arr_list[i]);
}
}
}
document.write("<h2>去除数字和字符之后：" + arr_list1 + "</h2><br /></br>")
//将得到的数组反转
var str2 = arr_list1.reverse()
document.write("<h2>反转之后的数组：" + str2 + "</h2></br><br />")
// 将数组反转之后重新转换为字符串
var str3 = str2.join("")
//将其全部转换成小写
var str4 = str3.toLowerCase()
//将字符串转成数组
var str5 = str4.split("")
//将数组首尾字母变大写
str5[0] = str5[0].toUpperCase();
str5[str5.length-1] = str5[str5.length-1].toUpperCase();
//将数组转成字符串
str5 = str5.join(" ");
//打印结果
document.write('<h2>最终的到的字符串：'+str5+'</h2>')
</script>
</head>
<body>
</body>
</html>
Date
- getFullYear (): obtain a four year value
- getMonth (): Gets the month, the value of 0-11
- getDate (): Days
- getHours (): Hours
- getMinutes (): the number of minutes
- getSeconds (): The number of seconds
- getMilliseconds (): number of milliseconds
- getDay (): day of the week, 0-6
- getTime (): total milliseconds (~ 1900)
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Date</title>
<script type="text/javascript">
// Date对象
var today = new Date();
var year = today.getFullYear();
var month = today.getMonth()+1;
var date = today.getDate();
var hours = today.getHours();
var minutes = today.getMinutes();
var seconds = today.getSeconds();
var week = today.getDay();
var timer = today.getTime();
var str1 = year+"年"+month+"月"+date+"日"+hours+" "+minutes+"分"+seconds+" 秒"+milliSec+"毫秒 总毫秒："+timer+"ms";
document.write(str1);
</script>
</head>
<body>
</body>
</html>
