Home Web Front-end JS Tutorial A detailed introduction to JavaScript strings

A detailed introduction to JavaScript strings

Jun 28, 2017 pm 01:44 PM
javascript js string

String in JavaScript is represented by characters enclosed in '' or "". The following article will introduce you to the relevant knowledge of JavaScript strings. Friends who are interested should take a look.

JavaScript strings are represented by characters enclosed in '' or "".

If ' itself is also a character, it can be enclosed by "". For example, "I'm OK" contains the six characters I, ', m, space, O, and K.

What if the string contains both ' and "? It can be identified by the escape character \, for example: the string represented by


'I\'m \"OK\"!';
Copy after login

The content is: I'm "OK"!

The escape character \ can escape many characters, such as \n represents a newline, \t represents a tab character, and the character \ itself must also be escaped, so \\ The character represented is \.

ASCII characters can be represented in hexadecimal format in the form of \x##, for example:


'\x41'; // 完全等同于 'A'
Copy after login

can also be represented by \u

# represents a Unicode character:


'\u4e2d\u6587'; // 完全等同于 '中文'
Copy after login
Multi-line string

due to multiple lines It is more troublesome to write strings using \n, so the latest ES6 standard adds a new method of expressing multi-line strings, using `...` to express:

`This is a

Multiple lines

String`;

Template string

To have multiple strings To connect

, you can use the + sign to connect:


var name = '小明';
var age = 20;
var message = '你好, ' + name + ', 你今年' + age + '岁了!';
alert(message);
Copy after login

If there are many variables that need to be connected, it will be more troublesome to use the + sign. ES6 has a new template character. String, the representation method is the same as the above multi-line string, but it will automatically replace the variables in the string:


var name = '小明';
var age = 20;
var message = `你好, ${name}, 你今年${age}岁了!`;
alert(message);
Copy after login
Operation string

Common operations on strings are as follows:


var s = 'Hello, world!';
s.length; // 13
Copy after login
To get the characters at a specified position in the string, use an Array-like The index operation, index

starts from 0:


var s = 'Hello, world!';
s[0]; // 'H'
s[6]; // ' '
s[7]; // 'w'
s[12]; // '!'
s[13]; // undefined 超出范围的索引不会报错,但一律返回undefined
Copy after login

It should be noted that the string is immutable. There will be no errors in assigning an index, but there will be no effect:


var s = 'Test';
s[0] = 'X';
alert(s); // s仍然为'Test'
Copy after login

JavaScript provides some common methods for strings. Note that calling these methods itself does not Will change the content of the original string, but return a new string:

toUpperCase

toUpperCase() Change to uppercase:


var s = 'Hello';
s.toUpperCase(); // 返回'HELLO'
Copy after login
toLowerCase

##toLowerCase() changes a string to all lowercase :


var s = 'Hello';
var lower = s.toLowerCase(); // 返回'hello'并赋值给变量lower
lower; // 'hello'
Copy after login

indexOf


##

indexOf()会搜索指定字符串出现的位置:
var s = 'hello, world';
s.indexOf('world'); // 返回7
s.indexOf('World'); // 没有找到指定的子串,返回-1
Copy after login

substring


substring()返回指定索引区间的子串:
var s = 'hello, world'
s.substring(0, 5); // 从索引0开始到5(不包括5),返回'hello'
s.substring(7); // 从索引7开始到结束,返回'world'
Copy after login

The above is the detailed content of A detailed introduction to JavaScript strings. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Recommended: Excellent JS open source face detection and recognition project Recommended: Excellent JS open source face detection and recognition project Apr 03, 2024 am 11:55 AM

Face detection and recognition technology is already a relatively mature and widely used technology. Currently, the most widely used Internet application language is JS. Implementing face detection and recognition on the Web front-end has advantages and disadvantages compared to back-end face recognition. Advantages include reducing network interaction and real-time recognition, which greatly shortens user waiting time and improves user experience; disadvantages include: being limited by model size, the accuracy is also limited. How to use js to implement face detection on the web? In order to implement face recognition on the Web, you need to be familiar with related programming languages ​​and technologies, such as JavaScript, HTML, CSS, WebRTC, etc. At the same time, you also need to master relevant computer vision and artificial intelligence technologies. It is worth noting that due to the design of the Web side

How to determine whether a Golang string ends with a specified character How to determine whether a Golang string ends with a specified character Mar 12, 2024 pm 04:48 PM

Title: How to determine whether a string ends with a specific character in Golang. In the Go language, sometimes we need to determine whether a string ends with a specific character. This is very common when processing strings. This article will introduce how to use the Go language to implement this function, and provide code examples for your reference. First, let's take a look at how to determine whether a string ends with a specified character in Golang. The characters in a string in Golang can be obtained through indexing, and the length of the string can be

How to intercept a string in Go language How to intercept a string in Go language Mar 13, 2024 am 08:33 AM

Go language is a powerful and flexible programming language that provides rich string processing functions, including string interception. In the Go language, we can use slices to intercept strings. Next, we will introduce in detail how to intercept strings in Go language, with specific code examples. 1. Use slicing to intercept a string. In the Go language, you can use slicing expressions to intercept a part of a string. The syntax of slice expression is as follows: slice:=str[start:end]where, s

How to repeat a string in python_python repeating string tutorial How to repeat a string in python_python repeating string tutorial Apr 02, 2024 pm 03:58 PM

1. First open pycharm and enter the pycharm homepage. 2. Then create a new python script, right-click - click new - click pythonfile. 3. Enter a string, code: s="-". 4. Then you need to repeat the symbols in the string 20 times, code: s1=s*20. 5. Enter the print output code, code: print(s1). 6. Finally run the script and you will see our return value at the bottom: - repeated 20 times.

Detailed explanation of the method of converting int type to string in PHP Detailed explanation of the method of converting int type to string in PHP Mar 26, 2024 am 11:45 AM

Detailed explanation of the method of converting int type to string in PHP In PHP development, we often encounter the need to convert int type to string type. This conversion can be achieved in a variety of ways. This article will introduce several common methods in detail, with specific code examples to help readers better understand. 1. Use PHP’s built-in function strval(). PHP provides a built-in function strval() that can convert variables of different types into string types. When we need to convert int type to string type,

How to check if a string starts with a specific character in Golang? How to check if a string starts with a specific character in Golang? Mar 12, 2024 pm 09:42 PM

How to check if a string starts with a specific character in Golang? When programming in Golang, you often encounter situations where you need to check whether a string begins with a specific character. To meet this requirement, we can use the functions provided by the strings package in Golang to achieve this. Next, we will introduce in detail how to use Golang to check whether a string starts with a specific character, with specific code examples. In Golang, we can use HasPrefix from the strings package

How to solve the problem of Chinese garbled characters when converting hexadecimal to string in PHP How to solve the problem of Chinese garbled characters when converting hexadecimal to string in PHP Mar 04, 2024 am 09:36 AM

Methods to solve Chinese garbled characters when converting hexadecimal strings in PHP. In PHP programming, sometimes we encounter situations where we need to convert strings represented by hexadecimal into normal Chinese characters. However, in the process of this conversion, sometimes you will encounter the problem of Chinese garbled characters. This article will provide you with a method to solve the problem of Chinese garbled characters when converting hexadecimal to string in PHP, and give specific code examples. Use the hex2bin() function for hexadecimal conversion. PHP’s built-in hex2bin() function can convert 1

The relationship between js and vue The relationship between js and vue Mar 11, 2024 pm 05:21 PM

The relationship between js and vue: 1. JS as the cornerstone of Web development; 2. The rise of Vue.js as a front-end framework; 3. The complementary relationship between JS and Vue; 4. The practical application of JS and Vue.

See all articles