ES6扩展

模板字符串和标签模板

const getcourselist = function() {
        // ajax
        return {
            status: true,
            msg: '获取成功',
            data: [{
                id: 1,
                title: 'vue 入门',
                date: 'xxxx-01-09'
            }, {
                id: 2,
                title: 'es6 入门',
                date: 'xxxx-01-10'
            }, {
                id: 3,
                title: 'react入门',
                date: 'xxxx-01-11'
            }]
        }
    };

    const { data: listdata, status, msg } = getcourselist();

    function foo(val) {
        return val.replace('xxxx', '2020');
    }

    if (status) {
        let arr = [];

        listdata.foreach(function({ date, title }) {

            arr.push(
                `
                    <li>
                        <span>${ `课程名: ${ title }` }</span>
                        <span>${ foo(date) }</span>
                    </li>
                `
            );

        });

        let ul = document.createelement('ul');
        ul.innerhtml = arr.join('');

        document.body.appendchild(ul);

    } else {
        alert(msg);
    }

padstart padend

    {
        let str = 'i';
        // 插入在5的位置
        let str1 = str.padstart(5, 'mooc');
        console.log(str1);
        // 倒序插入在5的位置
        let str2 = str.padend(5, 'mooc');
        console.log(str2);
    }

repeat

    {
        function repeat(str, num) {
            return new array(num + 1).join(str);
        }
        console.log(repeat('s', 3));
    }

startswith endswith

    {
        const str = 'a promise is a promsie';

        console.log(str.startswith('b'));
        console.log(str.startswith('a pro'));

        console.log(str.endswith('promsie'));
        console.log(str.endswith('a'));
    }

includes

    {
        const str = 'a promise is a promise';
        if (~str.indexof('promise')) {
            console.log('存在"promise"');
        }

        if (str.includes('a promise')) {
            console.log('存在"a promise"');
        }
    }

字符串转数组+遍历

    let str = 'promise';
    // 四种方法：转成数组后遍历
    var ostr = array.prototype.slice.call(str);
    var ostr = str.split('');
    const ostr = [...str];
    const [...ostr] = str;
    console.log(ostr);
    //单个字符输出
    ostr.foreach(function(word) {
        console.log(word);
    });

对全是英文的字符串中的大写字符加密 a -> 100  b -> 99

    const map = {a: '100', b: '99', c: '98', d: '97', e: '96', f: '95', g: '94', h: '93', i: '92', j: '91', k: '90', l: '89', m: '88', n: '87', o: '86', p: '85', q: '84', r: '83', s: '82', t: '81', u: '80', v: '79',w: '78',x: '77',y: '76', z: '75'};
    const words = 'abcdefghijklmnopqrstuvwxyz';

    ostr.foreach(function(word, index) {
        if (words.includes(word)) ostr[index] = map[word];
    });
    console.log(ostr.join(''));

使用for-of遍历字符串

    let str = 'promise';
    let newstr = '';
    const map = {a: '100', b: '99', c: '98', d: '97', e: '96', f: '95', g: '94', h: '93', i: '92', j: '91', k: '90', l: '89', m: '88', n: '87', o: '86', p: '85', q: '84', r: '83', s: '82', t: '81', u: '80', v: '79',w: '78',x: '77',y: '76', z: '75'};
    for (let word of str) {
        if (str.includes(word)) newstr += map[word];
    }
    console.log(newstr);

unicode是一项标准，包括字符集、编码方案等
解决传统的字符编码方案的局限