JavaScript Concise tutorial (2) string

The escape character \ can escape many characters, such as \ n for newline, \ t for tabs, and the character \ itself to be escaped, so \ \ is the character that \ \.
ASCII characters can be #形式的十六进制表示 in \x#, for example:

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001	‘\x41‘; // 完全等同于 ‘A‘

You can also use \u### #表示一个Unicode字符:

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001	‘\u4e2d\u6587‘; // 完全等同于 ‘中文‘

Because multiline strings are more cumbersome to write, the newest ES6 standard adds a multi-line string representation, denoted by ' ... ':

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`这是一个多行字符串`;

Common actions for strings are as follows:

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vars = ‘Hello, world!‘;s.length; // 13

To get a character at a specified position in a string, use an array-like subscript operation with the index number starting at 0:

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vars = ‘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

It is important to note that the string is immutable, and there is no error if you assign a value to an index of the string, but it does not have any effect:

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vars = ‘Test‘;s[0] = ‘X‘;alert(s); // s仍然为‘Test‘

JavaScript provides some common methods for strings, note that calling these methods does not alter the contents of the original string, but instead returns a new string:
toUpperCase
toUpperCase () turns a string all uppercase:

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vars = ‘Hello‘;[/size][size=3]s.toUpperCase(); // 返回‘HELLO‘

toLowerCase
toLowerCase () turns a string all lowercase:

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vars = ‘Hello‘;varlower = s.toLowerCase(); // 返回‘hello‘并赋值给变量lowerlower; // ‘hello‘

IndexOf
IndexOf () searches for the location where the specified string appears:

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vars = ‘hello, world‘;s.indexOf(‘world‘); // 返回7s.indexOf(‘World‘); // 没有找到指定的子串，返回-1

Substring
SUBSTRING () returns the substring of the specified index interval:

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vars = ‘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‘

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JavaScript Concise tutorial (2) string