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);

    }

    {

        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);

    }

    {

        function repeat(str, num) {

            return new Array(num + 1).join(str);

        }

        console.log(repeat('s', 3));

    }

    {

        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'));

    }

    {

        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"');

        }

    }

    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);

    });

    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(''));

    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);