string扩展方法使用

console.log('\u0061',"\u{5409}");
console.log('\u{41}','\u{42}');
console.log('\uD842\uDFB7','中文');
let s='吉𠮷A';
// @ts-ignore
console.log(s.length,s.charAt(0),s.charAt(1),s.charCodeAt(0),s.charCodeAt(1),s.codePointAt(0).toString(16).toUpperCase());

console.log(0xFFFF);
// @ts-ignore
console.log('中'.codePointAt(0),0xFFFF);
// @ts-ignore
console.log('中'.codePointAt(0) > 0xFFFF);
console.log(String.fromCharCode(0x20BB7));
// @ts-ignore
console.log(String.fromCodePoint(0x20BB7));
console.log(s.at(0));

console.log('\u01D1'==='\u004F\u030C','\u01D1'.length,'\u004F\u030C'.length);

// @ts-ignore
//NFC表示返回合成字符,默认参数, NFD返回分解多个字符
console.log('\u01D1'.normalize()==='\u004F\u030C'.normalize("NFC"),'\u01D1'.length,'\u004F\u030C'.length);

let testStr="ABCDEFG";
// @ts-ignore
console.log(testStr.startsWith('AB'));
// @ts-ignore
console.log(testStr.endsWith('FG'));
// @ts-ignore
console.log(testStr.includes('CD'));

// @ts-ignore
console.log(testStr.startsWith('AB',0));
// @ts-ignore
console.log(testStr.endsWith('BC',3));//针对前面3个字符找BC
// @ts-ignore
console.log(testStr.includes('CD',2));

// @ts-ignore
console.log('中国'.repeat(10));
// @ts-ignore
console.log('Hello'.repeat(0));//清空""
// @ts-ignore
console.log('OK'.repeat(3.8));//取整,重复3次
//注:repeat不接受负数 ,大于0,小于1的小数参数,默认取0 ,NaN也视为0  字符串 如果 是数字,转换为对应数值,其它非数字视为 0

// @ts-ignore
console.log('xxx'.padStart(16,'0'));
// @ts-ignore
console.log('xxx'.padEnd(16,'0'));

//模板字符串
let china='中国';
console.log(`你好,${china}`);

function getString(){
    return '这个世界很坏';
}

console.log(`${getString()}`);

let str1='1,2,3,4,5,';
let str2='6,7,8,9,0';
let str3=str1.concat(str2);
console.log(str3);
console.log(str3.split(','));