1.String: Stores a string and provides the properties and methods needed to process strings.
1. Create String object: explicit and implicit
<DOCTYPE html>
<html>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
<head>
<title>js函数</title>
</head>
<script type="text/javascript">
//申明String对象的两种方式：显式和隐式申明
//1.隐式
var myString="abc";
document.write(myString+"<br/>");
//2.显式
var myString2=new String("abc");
document.write(myString2+"<br/>");
</script>
<body>
</body>
</html>
*Explicitly and implicitly declared String objects have different types: the implicitly declared string object has type string, while the explicitly declared string object has type object.
*The real difference between explicit and implicit string creation is that if you want to reuse the same string, explicitly creating the string is more efficient;
* Explicitly creating strings also helps the JavaScript interpreter confuse numbers and strings;
2. Methods of using String objects
String object has many methods, only two are discussed here. indexOf() and substring() methods; pay attention to case.
*What you need to know: JavaScript strings are composed of characters. Each of these characters has an index. The index is 0-based, so the first position has an index of 0; the second position has an index of 1, and so on.
*The method indexOf() finds and returns the index position of the beginning of the substring. If the element being searched does not exist, it returns -1, otherwise it returns the index where the character is located. (lastIndexOf returns the position of the end of the substring)
Write an example below to determine whether the email address entered by the user number contains the @ symbol:
<DOCTYPE html>
<html>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
<head>
<title>js函数</title>
</head>
<script type="text/javascript">
//让用户输入Email地址，检查输入是否包含@符号
//使用prompt方法，获取用户输入的Email地址，检查是否包含@符号，使用indexof返回@符号的索引
var userInput=prompt("Please enter your email address","Email");
if(Number(userInput.indexOf("@"))==-1)
{
document.write("对不起，您输入的Email不合法");
}
else
{
document.write("恭喜您，您输入的Email通过验证");
}
</script>
<body>
</body>
</html>
substring() method uses the index of the starting position and ending position of the string as parameters to intercept a string from another string. You can return all strings from the first index to the end of the string without using the second parameter. For example, if we want to intercept all characters from the third to the sixth character, we can write like this:
<DOCTYPE html>
<html>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
<head>
<title>js函数</title>
</head>
<script type="text/javascript">
//从起始位置，到结束位置
var myhello="Hello Javascript World";
var newMyhello= myhello.substring(0);
document.write(newMyhello+"<br/>");
//从第三个字符到第六个字符
var myhello="Hello Javascript World";
var newMyhello= myhello.substring(2,5);
document.write(newMyhello+"<br/>");
</script>
<body>
</body>
</html>
The above is the entire content of this article, I hope you all like it.
es6数组怎么去掉重复并且重新排序May 05, 2022 pm 07:08 PM去掉重复并排序的方法：1、使用“Array.from(new Set(arr))”或者“[…new Set(arr)]”语句，去掉数组中的重复元素，返回去重后的新数组；2、利用sort()对去重数组进行排序，语法“去重数组.sort()”。
JavaScript的Symbol类型、隐藏属性及全局注册表详解Jun 02, 2022 am 11:50 AM本篇文章给大家带来了关于JavaScript的相关知识，其中主要介绍了关于Symbol类型、隐藏属性及全局注册表的相关问题，包括了Symbol类型的描述、Symbol不会隐式转字符串等问题，下面一起来看一下，希望对大家有帮助。
原来利用纯CSS也能实现文字轮播与图片轮播！Jun 10, 2022 pm 01:00 PM怎么制作文字轮播与图片轮播？大家第一想到的是不是利用js，其实利用纯CSS也能实现文字轮播与图片轮播，下面来看看实现方法，希望对大家有所帮助！
JavaScript对象的构造函数和new操作符（实例详解）May 10, 2022 pm 06:16 PM本篇文章给大家带来了关于JavaScript的相关知识，其中主要介绍了关于对象的构造函数和new操作符，构造函数是所有对象的成员方法中，最早被调用的那个，下面一起来看一下吧，希望对大家有帮助。
JavaScript面向对象详细解析之属性描述符May 27, 2022 pm 05:29 PM本篇文章给大家带来了关于JavaScript的相关知识，其中主要介绍了关于面向对象的相关问题，包括了属性描述符、数据描述符、存取描述符等等内容，下面一起来看一下，希望对大家有帮助。
javascript怎么移除元素点击事件Apr 11, 2022 pm 04:51 PM方法：1、利用“点击元素对象.unbind("click");”方法，该方法可以移除被选元素的事件处理程序；2、利用“点击元素对象.off("click");”方法，该方法可以移除通过on()方法添加的事件处理程序。
整理总结JavaScript常见的BOM操作Jun 01, 2022 am 11:43 AM本篇文章给大家带来了关于JavaScript的相关知识，其中主要介绍了关于BOM操作的相关问题，包括了window对象的常见事件、JavaScript执行机制等等相关内容，下面一起来看一下，希望对大家有帮助。
foreach是es6里的吗May 05, 2022 pm 05:59 PMforeach不是es6的方法。foreach是es3中一个遍历数组的方法，可以调用数组的每个元素，并将元素传给回调函数进行处理，语法“array.forEach(function(当前元素,索引,数组){...})”；该方法不处理空数组。
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
Hot Tools
Atom editor mac version download
The most popular open source editor
VSCode Windows 64-bit Download
A free and powerful IDE editor launched by Microsoft
MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.
SublimeText3 Linux new version
SublimeText3 Linux latest version
mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),
