What is a string in JavaScript learning? Introduction to js string related knowledge

This article will bring you JavaScript learning: What is a string? Introduction to js string related knowledge. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

JavaScript Strings

JavaScript strings are used to store and process text.

A string can store a series of characters, such as "HAHA";

A string is any character that can be inserted into quotation marks, you can Use single quotes or double quotes.

For example:

76c82f278ac045591c9159d381de2c57
100db36a723c770d327fc0aef2ce13b1
	93f0f5c25f18dab9d176bd4f6de5d30e
		a80eb7cbb6fff8b0ff70bae37074b813
		b2386ffb911b14667cb8f0f91ea547a7Insert title here6e916e0f7d1e588d4f442bf645aedb2f
	9c3bca370b5104690d9ef395f2c5f8d1
	6c04bd5ca3fcae76e30b72ad730ca86d
    c0ca4318fdc222459c029ff21852f55054bdf357c58b8a65c66d7c19c8e4d114
    07171f7b852830ab5b9b61f2bf64a10b时间65281c5ac262bf6d81768915a4a77ac0
	36cc49f0c466276486e50c850b7e4956
	8019067d09615e43c7904885b5246f0a
    var stringa = "哈哈";    var stringb = '你好，你坏，你好坏！！';
	2cacc6d41bbb37262a98f745aa00fbf0
73a6ac4ed44ffec12cee46588e518a5e

You can use the index position to access each character in the string;

76c82f278ac045591c9159d381de2c57
100db36a723c770d327fc0aef2ce13b1
93f0f5c25f18dab9d176bd4f6de5d30e
a80eb7cbb6fff8b0ff70bae37074b813
b2386ffb911b14667cb8f0f91ea547a7Insert title here6e916e0f7d1e588d4f442bf645aedb2f
9c3bca370b5104690d9ef395f2c5f8d1
6c04bd5ca3fcae76e30b72ad730ca86d
    c0ca4318fdc222459c029ff21852f55054bdf357c58b8a65c66d7c19c8e4d114
    07171f7b852830ab5b9b61f2bf64a10b时间65281c5ac262bf6d81768915a4a77ac0
36cc49f0c466276486e50c850b7e4956
8019067d09615e43c7904885b5246f0a
    var stringa = "哈哈";    
    var stringb = '你好，你坏，你好坏！！';    //通过索引访问字符串中的每个字符    
    alert(stringb[3]);
2cacc6d41bbb37262a98f745aa00fbf0
73a6ac4ed44ffec12cee46588e518a5e

The index in the string starts from 0, that is to say, the index value of the first character is [0], the second is [1], and so on.

You can use quotation marks in a string. The quotation marks in the string should not be the same as the quotation marks that enclose the string.

For example:

 76c82f278ac045591c9159d381de2c57
100db36a723c770d327fc0aef2ce13b1
93f0f5c25f18dab9d176bd4f6de5d30e
a80eb7cbb6fff8b0ff70bae37074b813
b2386ffb911b14667cb8f0f91ea547a7Insert title here6e916e0f7d1e588d4f442bf645aedb2f
9c3bca370b5104690d9ef395f2c5f8d1
6c04bd5ca3fcae76e30b72ad730ca86d
    c0ca4318fdc222459c029ff21852f55054bdf357c58b8a65c66d7c19c8e4d114
    07171f7b852830ab5b9b61f2bf64a10b时间65281c5ac262bf6d81768915a4a77ac0
36cc49f0c466276486e50c850b7e4956
8019067d09615e43c7904885b5246f0a
    var stringa = "哈'dd'哈";
    var stringb = '你好，"你坏"，你好坏！！';
    //通过索引访问字符串中的每个字符
    alert(stringb[3]);
2cacc6d41bbb37262a98f745aa00fbf0
73a6ac4ed44ffec12cee46588e518a5e

You can also add escape characters to the string to use quotation marks \ is the escape character

For example:

76c82f278ac045591c9159d381de2c57
100db36a723c770d327fc0aef2ce13b1
93f0f5c25f18dab9d176bd4f6de5d30e
a80eb7cbb6fff8b0ff70bae37074b813
b2386ffb911b14667cb8f0f91ea547a7Insert title here6e916e0f7d1e588d4f442bf645aedb2f
9c3bca370b5104690d9ef395f2c5f8d1
6c04bd5ca3fcae76e30b72ad730ca86d
    c0ca4318fdc222459c029ff21852f55054bdf357c58b8a65c66d7c19c8e4d114
    07171f7b852830ab5b9b61f2bf64a10b时间65281c5ac262bf6d81768915a4a77ac0
36cc49f0c466276486e50c850b7e4956
8019067d09615e43c7904885b5246f0a
    var stringa = "哈\'dd\'哈";
    var stringb = '你好，\"你坏\"，你好坏！！';
    //通过索引访问字符串中的每个字符
    alert(stringb[3]);
2cacc6d41bbb37262a98f745aa00fbf0
73a6ac4ed44ffec12cee46588e518a5e

String length

can be calculated using the built-in property length The length of the string:

For example:

76c82f278ac045591c9159d381de2c57
100db36a723c770d327fc0aef2ce13b1
93f0f5c25f18dab9d176bd4f6de5d30e
a80eb7cbb6fff8b0ff70bae37074b813
b2386ffb911b14667cb8f0f91ea547a7Insert title here6e916e0f7d1e588d4f442bf645aedb2f
9c3bca370b5104690d9ef395f2c5f8d1
6c04bd5ca3fcae76e30b72ad730ca86d
    c0ca4318fdc222459c029ff21852f55054bdf357c58b8a65c66d7c19c8e4d114
    07171f7b852830ab5b9b61f2bf64a10b时间65281c5ac262bf6d81768915a4a77ac0
36cc49f0c466276486e50c850b7e4956
8019067d09615e43c7904885b5246f0a
    var stringa = "哈\'dd\'哈";
    var stringb = '你好，\"你坏\"，你好坏！！';
    //通过索引访问字符串中的每个字符
    alert(stringb.length);//查看字符串stringb的长度
2cacc6d41bbb37262a98f745aa00fbf0
73a6ac4ed44ffec12cee46588e518a5e

Special characters

In JavaScript, characters are written in single quotes or double quotes.

Otherwise, strings similar to this cannot be parsed →_→ "Wahahaha" lala "mommy";

How to solve it? ? ? Just use escape characters, →_→ "Wahahaha\"Lala\"Momada";

\ is the escape character, which is to convert special characters is a string character. See the table below for details

##Strings can be objects

Usually JavaScript strings are primitive values ​​and can be created using characters: var aa= "AA";

However, you can also use the new keyword to define a string as an object: var stringaa = new String("Enron");

It is generally not recommended to create a String object, which will affect the execution speed and may cause Other effects.

For example:

var aa = "AA";
var bb = new String("AA");
alert(aa === bb); //返回值是false    因为  aa是字符串   bb 是对象

String properties and methods

Primitive strings have no properties or methods because they are not objects.

Primitive value strings can use JavaScript properties and methods, because JavaScript can treat primitive values ​​as objects when executing methods and properties.

String properties

##String methods

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