[JavaScript-02]FOR WHILE循环

1. 语句

// For语句
for (let index = 0; index <=6; index++) 
{
    console.log(`For Loop Number:${index}`);    
}

// While语句
let i = 0;
while (i <=6) {
    console.log(`While Loop Number:${i}`);
    i++;
}

2. for应用

// For 应用
const todos =
[
    {
        id          : 1,
        text        : 'Take out trash',
        isCompleted : true
    },
    {
        id          : 2,
        text        : 'Meeting with boss',
        isCompleted : true
    },
    {
        id          : 3,
        text        : 'Dentist appt',
        isCompleted : false
    },
];
// 索引遍历
for (let i=0;i<todos.length;i++) 
{
    console.log('todos[i].text:',todos[i].text);
}
// 内容遍历
for (let t of todos)
{
    console.log('t.id:',t.id);
}

3. forEach, map, filter

// forEach
todos.forEach
(
    function(t)
    {
        console.log('t.text:',t.text);
    }
);
// map 和 filter 的区别 map返回数组，filter返回符合条件的数组
// map 返回数组
const t = todos.map
(
    function (t) 
    {
        return t.id;    
    }
);
console.log('t:',t);

// filter过滤器
// === Python ==
const tCompleted = todos.filter
(
    function(t)
    {
        return t.isCompleted === true;
    }
);
console.log('tCompleted:',tCompleted);

const ttCompleted = todos.filter
(
    function(t)
    {
        return t.isCompleted === true;
    }
).map
(
    function(t)
    {
        return t.text;
    }
);
console.log('ttCompleted:',ttCompleted);

END