ES6语法学习笔记(4)-字符串扩展

{
    console.log('a','\u0061');//a a
    console.log('a','\u20BB7');//a ₻7
    console.log('s','\u{20BB7}')//s ?
}


{
    // ES5
    let s='?';
    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
    let s1='?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
}

取码值

{
    // ES5
    console.log(String.fromCharCode("0x20bb7"));//ஷ
    // ES6
    console.log(String.fromCodePoint("0x20bb7"));//?
}

遍历字符串

// ES5
{
    let str='\u{20bb7}abc';
    for(let i=0;i

}
判断字符串中包含某些字符，起始截止

{
    let str="string";
    console.log('includes',str.includes("r"));//true
    console.log('start',str.startsWith("str"));//true
    console.log('end',str.endsWith("ng"));//true
}

重复字符串

{
    let str="abc";
    console.log(str.repeat(2));//abcabc
}

ES6中的模板字符串

{
    let name="list";
    let info="hello world";
    let m=im ${name},${info};//数字1左边的键`,数值项用${变量}
    console.log(m);//im list,hello worldim list,hello world
}

ES7中的草案，加babel-polyfill在ES6中也可以使用

{
    console.log('1'.padStart(2,'0'));//此api常用日期中补白，向前补 01
    console.log('1'.padEnd(2,'0'));//此api常用日期中补白，向后补 10
}

标签模板,1.用于字符串过滤，防止XML攻击2.处理多语言转换

{
    let user={
        name:'list',
        info:'hello world'
    };
    console.log(abci am ${user.name},${user.info});//i am ,,,listhello world
    function abc(s,v1,v2){
        console.log(s,v1,v2);//["i am ", ",", "", raw: Array(3)] "list" "hello world"
        return s+v1+v2;
    }
}



{
   console.log(String.rawHi\n${1+2});//String.raw用于转意 Hi\n3
   console.log(Hi\n${1+2});//Hi
   // 3
}