JavaScript - 文本格式化

字符串

字符串字面表达

\'foo\'
\"bar\"

Hexadecimal转义序列

\'\\xA9\' // \"©\"

Unicode转义序列

\'\\u00A9\' // \"©\"

Unicode code point escape

\'\\u{2F804}\'

// the same with simple Unicode escapes
\'\\uD87E\\uDC04\'

字符串对象

字符串对象是对原始字符串数据类型的封装

const foo = new String(\'foo\'); // Creates a String  
console.log(foo); // Displays: [String: \'foo\']
typeof foo; // Returns \' \'

const firstString = \'2 + 2\'; // Creates a string literal value
const secondString = new String(\'2 + 2\'); // Creates a String  
eval(firstString); // Returns the number 4
eval(secondString); // Returns the string \"2 + 2\"

const hello = \'Hello, World!\';
const helloLength = hello.length;
hello[0] = \'L\'; // This has no effect, because strings are immutable
hello[0]; // This returns \"H\"

字符串对象的方法