es6基础(4)--字符串扩展

//字符串扩展
{
    console.log('a','\u0061');
    console.log('s','\u20BB7');//超过了0xffff

    console.log('s','\u{20BB7}');//如果超过就用{}包裹

}
{
    //es5中
    let s='𠮷';
    console.log('length',s.length);//length 2
    console.log('0',s.charAt(0));//0 �
    console.log('1',s.charAt(1));//1 �
    console.log('at0',s.charCodeAt(0));//at0 55362
    console.log('at1',s.charCodeAt(1));//at1 57271

    //es6中
    let s1='𠮷a';
    console.log('length',s1.length);//length 3
    console.log('code0',s1.codePointAt(0));//code0 134071
    console.log('code0',s1.codePointAt(0).toString(16));//code0 20bb7
    console.log('code1',s1.codePointAt(1));//code1 57271
    console.log('code2',s1.codePointAt(2));//code2 97
}

{
    console.log(String.fromCharCode("0x20bb7"));//ஷ
    console.log(String.fromCodePoint("0x20bb7"));//𠮷
}
{
    let str='\u{20bb7}abc';
    for(let i=0;i<str.length;i++){
        console.log('es5',str[i]);
        //es5 �
        //es5 �
        //es5 a
        //es5 b
        //es5 c
    }
    for(let code of str){
        console.log('es6',code)
        //es6 𠮷
        //es6 a
        //es6 b
        //es6 c
    }
}
{
    let str="string";
    //includes,判断是否包含字符串('x'）
    console.log('includes',str.includes('r'));
    console.log('includes',str.includes('c'));
    //startsWidth,判断是否('xx')字符串起始
    console.log('start',str.startsWith('str'));
    //endsWith,判断是否('xx')字符串结尾
    console.log('end',str.endsWith('str'));
}
{
    let str="abc";
    //字符串的复制(x)，x次数
    console.log(str.repeat(2));//abcabc
}
//字符串模板内容，拼接
{
    let name="list";
    let info="hello world";
    let m=`i am ${name},${info}`;
    console.log(m);//i am list,hello world
}

{    
    //向前补，一共两位，(位数,补的字符)
    console.log('1'.padStart(2,'0'));//01
    //向后补，一共两位，(位数,补的字符)
    console.log('1'.padEnd(2,'0'));//10
}
//标签模板
    //1.过滤字符串的时候，防止攻击的时候
    //2.多语言转换
{
    let user={
        name:'list',
        info:'hello world'
    };
    console.log(abc`i am ${user.name},${user.info}`);
    function abc(s,v1,v2){
        console.log(s,v1,v2);
        return s+v1+v2;
    }
}

{    
    //String.raw可以不转义\n
    console.log(String.raw`Hi\n${1+2}`);//Hi\n3
    console.log(`Hi\n${1+2}`);
    //Hi
    //3
}